CI: add job to publish collection on galaxy

Copied from stackhpc.pulp

Author: markgoddard

.github/workflows/publish.yml

@@ -0,0 +1,22 @@
+
+name: Publish
+
+# Controls when the action will run.
+on:
+  push:
+    tags:
+      - "v[0-9]+.[0-9]+.[0-9]+"
+  workflow_dispatch:
+
+jobs:
+  galaxy:
+    runs-on: ubuntu-latest
+
+    steps:
+      # Checks-out the repository under $GITHUB_WORKSPACE, so it's accessible to the job
+      - uses: actions/checkout@v2
+
+      - name: Build and publish a collection
+        uses: artis3n/ansible_galaxy_collection@v2
+        with:
+          api_key: '${{ secrets.GALAXY_API_KEY }}'