refctor: Stop using poetry

Using poetry merely for running pre-commit is overkill. Especially, given
the pre-commit GitHub action either way ignored our setup and
downloaded and used the latest pre-commit version.
pre-commit is an established tool with a stable behavior. All users can
be expected to install it for themselves. Furthermore, we can ensure a
fairly recent version is used via the pre-commit config.

.github/workflows/ci.yaml

@@ -7,18 +7,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v4
-      - uses: snok/install-poetry@v1
-        with:
-          virtualenvs-create: true
-          virtualenvs-in-project: true
-          installer-parallel: true
       - uses: actions/setup-python@v5
-        with:
-          python-version: "3.10"
-          cache: 'poetry'
-      - name: Install dependencies
-        run: poetry install --no-interaction --no-root
-      - run: source .venv/bin/activate
       - uses: pre-commit/[email protected]
 
   fast-tests:

.pre-commit-config.yaml

@@ -1,3 +1,5 @@
+minimum_pre_commit_version: 4.0.0
+
 define: &generated_doc_files "^docs/(cc_info_mapping|dwyu_aspect).md"
 
 repos:

test_basic.sh

@@ -6,7 +6,7 @@ set -o nounset
 echo ""
 echo "Pre-commit checks"
 echo ""
-poetry run pre-commit run --all-files
+pre-commit run --all-files
 
 echo ""
 echo "Execute unit tests"