Make package comparison steps optional in CI for the sake of forks

Forks won't always have the `latest` tag (and even if they do it might be very stale), so don't bother with package comparison unless the fork explicitly enables it

.github/workflows/Bonsai.yml

@@ -45,6 +45,9 @@ jobs:
       - name: Create build matrix
         id: create-matrix
         run: python .github/workflows/create-build-matrix.py
+        env:
+          enable_package_comparison: ${{vars.ENABLE_PACKAGE_COMPARISON}}
+          will_publish_packages: ${{github.event.inputs.will_publish_packages}}
 
   # =====================================================================================================================================================================
   # Build, test, and package
@@ -184,7 +187,7 @@ jobs:
     runs-on: ubuntu-latest
     # We technically only need the dummy build jobs, but GitHub Actions lacks the ability to depend on specific jobs in a matrix
     needs: build-and-test
-    if: github.event_name != 'pull_request'
+    if: github.event_name != 'pull_request' && vars.ENABLE_PACKAGE_COMPARISON == 'true'
     steps:
       # ----------------------------------------------------------------------- Checkout
       - name: Checkout

.github/workflows/create-build-matrix.py

@@ -43,10 +43,19 @@ def add_dummy(name: str, artifacts_suffix: str):
     dummy['artifacts-suffix'] = artifacts_suffix
     return dummy
 
-if os.getenv('GITHUB_EVENT_NAME') != 'pull_request':
+enable_package_comparison = os.getenv('enable_package_comparison') == 'true'
+github_event_name = os.getenv('GITHUB_EVENT_NAME')
+
+if github_event_name != 'pull_request' and enable_package_comparison:
     add_dummy('Previous Dummy', '-dummy-prev')['checkout-ref'] = 'refs/tags/latest'
     add_dummy('Next Dummy', '-dummy-next')
 
+# Fail early if we won't be able to do package comparison and the run must publish packages to make logical sense
+# Package comparison requires the `latest` tag to exist, but it will usually either be missing or invalid for forks so we require it to be opt-in
+if not enable_package_comparison:
+    if github_event_name == 'release' or (github_event_name == 'workflow_dispatch' and os.getenv('will_publish_packages') == 'true'):
+        gha.print_error('Release aborted. We would not be able to determine which packages need to be released as this repository is not configured for package comparison.')
+
 # Output
 matrix_json = json.dumps({ "include": matrix }, indent=2)
 print(matrix_json)