fix(ci): update ruff-action version to v4.0.0

Dependabot seems to have trouble switching to ___immutable releases___ like:
* https://github.com/astral-sh/ruff-action/releases/tag/v4.0.0

Author: cclauss

.github/workflows/tests.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v6
-    - uses: astral-sh/ruff-action@v3
+    - uses: astral-sh/ruff-action@v4.0.0
       with:
         args: "check --select=E,F,PLC,PLE,UP,W,YTT --ignore=E721,PLC0206,PLC0415,PLC1901,S101,UP031 --target-version=py39"
     - run: ruff format --check --diff