GitHub Actions: Add check executables problem matcher

.github/workflows/ci.yaml

@@ -255,6 +255,9 @@ jobs:
         run: |
           echo "Failed to restore Python virtual environment from cache"
           exit 1
+      - name: Register check executables problem matcher
+        run: |
+          echo "::add-matcher::.github/workflows/matchers/check-executables-have-shebangs.json"
       - name: Run executables check
         run: |
           . venv/bin/activate

.github/workflows/matchers/check-executables-have-shebangs.json

@@ -0,0 +1,14 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "check-executables-have-shebangs",
+      "pattern": [
+        {
+          "regexp": "^(.+):\\s(.+)$",
+          "file": 1,
+          "message": 2
+        }
+      ]
+    }
+  ]
+}