test: use filters to prevent redundant runs

Only when the code changed would tests has to be run. This prevents
the large test matrix from eating up the API quota.

.github/workflows/test.yml

@@ -13,6 +13,20 @@ on:
     - cron: "0 0 * * 0"
 
 jobs:
+  filter:
+    name: Check if tests should be run
+    runs-on: ubuntu-latest
+    outputs:
+      should-run: ${{ steps.filter.should_skip }}
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: fkirc/[email protected]
+        id: filter
+        with:
+          # Only run when code used by the action changed.
+          paths: '["dist/**", ".github/nimskull-problem-matcher.json"]'
+
   check:
     strategy:
       matrix: