chore: fix test-exemption job (#37)

.github/workflows/trigger-tests.yml

@@ -55,26 +55,29 @@ jobs:
     if: github.event_name == 'merge_group'
     runs-on: ubuntu-latest
     outputs:
-      # return 'false' if any files in the PR are not exempt, otherwise return 'true'
-      is-exempt: ${{ steps.changed-files.outputs.not-exempt_any_changed == 'true' && 'false' || 'true' }}
+      # return 'true' if any files in the PR are not exempt
+      not-exempt: ${{ steps.changed-files.outputs.not-exempt_any_modified }}
     steps:
+      - uses: hmarr/debug-action@v2
       - name: checkout
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: changed-files
         uses: tj-actions/changed-files@v39
         with:
-          base_sha: ${{ github.event.pull_request.base.ref || github.event.merge_group.base_ref }}
-          sha: ${{ github.event.pull_request.head.ref || github.event.merge_group.head_ref }}
+          base_sha: ${{ github.event.merge_group.base_sha }}
+          sha: ${{ github.event.merge_group.head_sha }}
+          fail_on_initial_diff_error: true
+          fail_on_submodule_diff_error: true
           files_yaml: |
             not-exempt:
               - '**'
               - '!**/*.md'
 
   skip-tests-if-merge-group-event-and-exemption-criteria-met:
     needs: test-exemption
-    if: github.event_name == 'merge_group' && needs.test-exemption.outputs.is-exempt == 'true'
+    if: github.event_name == 'merge_group' && needs.test-exemption.outputs.not-exempt != 'true'
     runs-on: ubuntu-latest
     steps:
       - name: skip-tests-if-merge-group-event-and-exemption-criteria-met
@@ -89,7 +92,7 @@ jobs:
 
   test-e2e-on-prem-lite:
     needs: test-exemption
-    if: github.event_name == 'merge_group' && needs.test-exemption.outputs.is-exempt == 'false'
+    if: github.event_name == 'merge_group' && needs.test-exemption.outputs.not-exempt == 'true'
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo