Update actions/checkout action to v6

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/main.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     container: fedorapython/fedora-python-tox:latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Mark the directory as safe for git
         run: git config --global --add safe.directory $PWD
@@ -36,7 +36,7 @@ jobs:
 
     steps:
 
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python
         uses: actions/setup-python@v6
         with: