try several subnets in random order until one succeeds. Minimize the InsufficientInstanceCapacity error

Ref machulav#60

Author: mgaitan

README.md

@@ -198,7 +198,7 @@ Now you're ready to go!
 | `github-token`                                                                                                                                                               | Always required.                           | GitHub Personal Access Token with the `repo` scope assigned.                                                                                                                                                                                                                                                                          |
 | `ec2-image-id`                                                                                                                                                               | Required if you use the `start` mode.      | EC2 Image Id (AMI). <br><br> The new runner will be launched from this image. <br><br> The action is compatible with Amazon Linux 2 images.                                                                                                                                                                                           |
 | `ec2-instance-type`                                                                                                                                                          | Required if you use the `start` mode.      | EC2 Instance Type.                                                                                                                                                                                                                                                                                                                    |
-| `subnet-id`                                                                                                                                                                  | Required if you use the `start` mode.      | VPC Subnet Id. <br><br> The subnet should belong to the same VPC as the specified security group.                                                                                                                                                                                                                                     |
+| `subnet-id`                                                                                                                                                                  | Required if you use the `start` mode.      | VPC Subnet Id or Json-encoded array of Subnet ids. <br><br> The subnet should belong to the same VPC as the specified security group.                                                                                                                                                                                                                                     |
 | `security-group-id`                                                                                                                                                          | Required if you use the `start` mode.      | EC2 Security Group Id. <br><br> The security group should belong to the same VPC as the specified subnet. <br><br> Only the outbound traffic for port 443 should be allowed. No inbound traffic is required.                                                                                                                          |
 | `label`                                                                                                                                                                      | Required if you use the `stop` mode.       | Name of the unique label assigned to the runner. <br><br> The label is provided by the output of the action in the `start` mode. <br><br> The label is used to remove the runner from GitHub when the runner is not needed anymore.                                                                                                   |
 | `ec2-instance-id`                                                                                                                                                            | Required if you use the `stop` mode.       | EC2 Instance Id of the created runner. <br><br> The id is provided by the output of the action in the `start` mode. <br><br> The id is used to terminate the EC2 instance when the runner is not needed anymore.                                                                                                                      |
@@ -250,13 +250,14 @@ jobs:
           aws-region: ${{ secrets.AWS_REGION }}
       - name: Start EC2 runner
         id: start-ec2-runner
-        uses: machulav/ec2-github-runner@v2
+        uses: shiphero/ec2-github-runner@v2
         with:
           mode: start
           github-token: ${{ secrets.GH_PERSONAL_ACCESS_TOKEN }}
           ec2-image-id: ami-123
           ec2-instance-type: t3.nano
-          subnet-id: subnet-123
+          subnet-id: > # will try each value in a random order until one succeeds.
+            ["subnet-123", "subnet-456"]    
           security-group-id: sg-123
           iam-role-name: my-role-name # optional, requires additional permissions
           aws-resource-tags: > # optional, requires additional permissions