chore(deps): update actions/checkout action to v6

.gitea/workflows/linting.yaml

@@ -14,7 +14,7 @@ jobs:
   pylint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.gitea/actions/poetrybuild
       - name: Lint with pylint
@@ -23,7 +23,7 @@ jobs:
   formatting:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.gitea/actions/poetrybuild
       - name: Test formatting with isort and black
@@ -34,7 +34,7 @@ jobs:
   mypy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.gitea/actions/poetrybuild
       - name: Test typing with mypy

.gitea/workflows/publish.yaml

@@ -11,7 +11,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Build and publish to PyPI
         uses: https://github.com/JRubics/poetry-publish@v2.1
         with:

.gitea/workflows/reuse.yaml

@@ -14,6 +14,6 @@ jobs:
   reuse:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Check REUSE Compliance
         uses: https://github.com/fsfe/reuse-action@v5

.gitea/workflows/selftests.yaml

@@ -16,7 +16,7 @@ jobs:
   test-build-install:
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Add pipx to PATH
         run: echo "/root/.local/bin" >> ${GITHUB_PATH}
       - name: Install poetry
@@ -34,7 +34,7 @@ jobs:
   test-sync:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.gitea/actions/poetrybuild
         # using minimal set of dependencies