Unpin dependencies in pipeline to catch breakages early, and add pre-commit run -a

If all goes well, this will cause the pipeline to complete
successfully but fail with a pre-commit error, which the next
commit will solve.

Author: JaapJoris

.github/workflows/main.yml

@@ -2,15 +2,21 @@ name: CI
 
 on:
   push:
-    branches:
-    - main
   pull_request:
 
 jobs:
-  tests:
-    name: Python ${{ matrix.python-version }}
-    runs-on: ubuntu-24.04
+  pre-commit:
+    name: Run pre-commit hooks
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout
+      - uses: actions/setup-python
+      - run: python -m pip install --upgrade pre-commit
+      - run: pre-commit run -a
 
+  tests:
+    name: Run tests using Python ${{ matrix.python-version }}
+    runs-on: ubuntu-latest
     strategy:
       matrix:
         python-version:
@@ -19,18 +25,10 @@ jobs:
         - '3.11'
         - '3.12'
         - '3.13'
-
     steps:
-    - uses: actions/checkout@v2
-
-    - uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip setuptools wheel
-        python -m pip install --upgrade nox
-
-    - name: Run tox targets for ${{ matrix.python-version }}
-      run: nox --session tests-${{ matrix.python-version }}
+      - uses: actions/checkout
+      - uses: actions/setup-python
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: python -m pip install --upgrade nox
+      - run: nox --session tests-${{ matrix.python-version }}