CI: add support for merge queue

.github/workflows/test-sanitizers.yml

@@ -1,32 +1,41 @@
 name: Check clang sanitizers
 
 on:
-  # always test main
-  push:
-    branches:
-      - main
+  pull_request:
   merge_group:
-  # ignore PRs due to time needed
-  # allow triggering tests, ignores skip check
+  #push:
+  #  branches: [ main ]
   workflow_dispatch:
 
 jobs:
   pre_job:
     runs-on: ubuntu-latest
     outputs:
-      should_skip: ${{ steps.skip_check.outputs.should_skip }}
+      should_skip: ${{ steps.set_output.outputs.should_skip }}
     steps:
       - id: skip_check
+        if: ${{ github.event_name != 'merge_group' }}
         uses: fkirc/skip-duplicate-actions@v5
         with:
           # don't run on documentation changes
           paths_ignore: '["**/README.md", "docs/**", "guidelines/**"]'
+          # cancel previous builds if a new commit is pushed
+          # but never cancel main
+          cancel_others: ${{ github.ref != 'refs/heads/main' }}
+
+      - id: set_output
+        run: |
+          if [ "${{ github.event_name }}" = "merge_group" ]; then
+            echo "should_skip=false" >> $GITHUB_OUTPUT
+          else
+            echo "should_skip=${{ steps.skip_check.outputs.should_skip }}" >> $GITHUB_OUTPUT
+          fi
 
   run_san:
     name: Build and run tests
     runs-on: ${{ matrix.os }}
     needs: pre_job
-    if: needs.pre_job.outputs.should_skip != 'true'
+    if: (github.event_name == 'merge_group' || github.event_name == 'workflow_dispatch') && needs.pre_job.outputs.should_skip != 'true'
     env:
       CC: clang
       ASAN_OPTIONS: halt_on_error=1
@@ -73,3 +82,10 @@ jobs:
         run: |
           find tests/**/*.err -print -exec cat {} \;
 
+  test-sanitizers-result:
+    runs-on: ubuntu-latest
+    needs:
+      - run_san
+    if: always() && !contains(join(needs.*.result, ','), 'failure') && !contains(join(needs.*.result, ','), 'cancelled')
+    steps:
+      - run: echo "All good"