chore(deps): update actions/checkout action to v6 (#35)

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

Author: renovate[bot]

.github/workflows/docker.yaml

@@ -17,7 +17,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Parse version
         id: version
         run: echo "VERSION=$(awk -F= '/^ARG SQLCMD_VERSION/ {print $2}' Dockerfile)" >> $GITHUB_OUTPUT