Don't attempt to create new PRs on PRs from forks (TuringLang#511)

.github/workflows/version_check.yml

@@ -30,6 +30,7 @@ jobs:
       # Determine whether the target branch is master (i.e. this is a push to
       # master or a PR to master).
       TARGET_IS_MASTER: ${{ (github.event_name == 'push' && github.ref_name == 'master') || (github.event_name == 'pull_request' && github.base_ref == 'master') }}
+      IS_PR_FROM_FORK: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.repo.fork }}
       # Disable precompilation as it takes a long time and is not needed for this workflow
       JULIA_PKG_PRECOMPILE_AUTO: 0
 
@@ -46,14 +47,16 @@ jobs:
           echo github.ref_name: ${{ github.ref_name }}
           echo github.base_ref: ${{ github.base_ref }}
           echo TARGET_IS_MASTER: ${{ env.TARGET_IS_MASTER }}
+          echo IS_PR_FROM_FORK: ${{ env.IS_PR_FROM_FORK }}
 
       - name: Check version consistency
+        id: version_check
         continue-on-error: true
         run: julia --color=yes .github/workflows/version_check.jl
 
       - name: Create a PR with suggested changes
         id: create_pr
-        if: env.TARGET_IS_MASTER
+        if: steps.version_check.outcome == 'failure' && env.TARGET_IS_MASTER && (! env.IS_PR_FROM_FORK)
         uses: peter-evans/create-pull-request@v6
         with:
           base: ${{ github.event_name == 'pull_request' && github.head_ref || github.ref_name }}
@@ -62,8 +65,8 @@ jobs:
           body: "This PR is automatically generated by the `version_check.yml` GitHub Action."
           title: "Update Turing.jl version to match latest release"
 
-      - name: Comment on PR about suggested changes
-        if: ${{ github.event_name == 'pull_request' && steps.create_pr.outputs.pull-request-operation == 'created' }}
+      - name: Comment on PR about suggested changes (if PR was made)
+        if: github.event_name == 'pull_request' && steps.create_pr.outputs.pull-request-operation == 'created'
         uses: thollander/actions-comment-pull-request@v2
         with:
           message: |