chore: remove test matrix

We don't have tests besides linting, which does not depend on the
installed Python version

Author: vlaci

.github/workflows/test.yml

@@ -9,10 +9,6 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
     - uses: actions/checkout@v4
@@ -25,7 +21,6 @@ jobs:
       with:
         enable-cache: true
         cache-dependency-glob: "uv.lock"
-        python-version: ${{ matrix.python-version }}
-    - name: Black source code formating check
+        python-version-file: "pyproject.toml"
       run: |
         uv run black --check .