capture deployment url for deploy hooks

Author: bradrydzewski

scm/driver/github/testdata/webhooks/deployment.json.golden

@@ -29,6 +29,7 @@
         "Created": "0001-01-01T00:00:00Z",
         "Updated": "0001-01-01T00:00:00Z"
     },
+    "Link": "https://api.github.com/repos/Codertocat/Hello-World/deployments/87972451",
     "Target": "production",
     "TargetURL": "",
     "Task": "deploy"

scm/driver/github/webhook.go

@@ -243,6 +243,7 @@ type (
 			Description    null.String `json:"description"`
 			Environment    null.String `json:"environment"`
 			EnvironmentURL null.String `json:"environment_url"`
+			URL            null.String `json:"url"`
 			Sha            null.String `json:"sha"`
 			Ref            null.String `json:"ref"`
 			Task           null.String `json:"task"`
@@ -358,6 +359,7 @@ func convertPullRequestHook(src *pullRequestHook) *scm.PullRequestHook {
 
 func convertDeploymentHook(src *deploymentHook) *scm.DeployHook {
 	dst := &scm.DeployHook{
+		Link: src.Deployment.URL.String,
 		Data: src.Deployment.Payload,
 		Desc: src.Deployment.Description.String,
 		Ref: scm.Reference{

scm/webhook.go

@@ -111,6 +111,7 @@ type (
 		Target    string
 		TargetURL string
 		Task      string
+		Link      string
 	}
 
 	// SecretFunc provides the Webhook parser with the