Publish release notes as a pre-release for milestones

This commit updates the "create-github-release" action to allow an
additional input that specifies whether this is a pre-release. If that
is the case, then the `--prerelease` flag is set.

Closes gh-33200

Author: snicoll

.github/actions/create-github-release/action.yml

@@ -7,6 +7,10 @@ inputs:
   token:
     description: 'Token to use for authentication with GitHub'
     required: true
+  prerelease:
+    description: 'Whether the release is a pre-release (milestone or release candidate)'
+    required: false
+    default: 'false'
 runs:
   using: composite
   steps:
@@ -20,4 +24,4 @@ runs:
       env:
         GITHUB_TOKEN: ${{ inputs.token }}
       shell: bash
-      run: gh release create ${{ format('v{0}', inputs.milestone) }} --notes-file changelog.md
+      run: gh release create ${{ format('v{0}', inputs.milestone) }} --notes-file changelog.md ${{ inputs.prerelease == 'true' && '--prerelease' || '' }}

.github/workflows/release-milestone.yml

@@ -72,3 +72,4 @@ jobs:
         with:
           milestone: ${{ needs.build-and-stage-release.outputs.version }}
           token: ${{ secrets.GH_ACTIONS_REPO_TOKEN }}
+          prerelease: 'true'