Update actions/checkout action to v6 (#176)

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

Author: renovate[bot]

.github/workflows/lint-check-types.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: pnpm/action-setup@v4
       - uses: actions/setup-node@v6
         with:

.github/workflows/persist-csv-database-to-cache.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: pnpm/action-setup@v4
       - uses: actions/setup-node@v6
         with:

.github/workflows/persist-csv-database-to-git.yml

@@ -13,7 +13,7 @@ jobs:
       # Write permissions for $GITHUB_TOKEN (to commit and push)
       contents: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: pnpm/action-setup@v4
       - uses: actions/setup-node@v6
         with:

.github/workflows/persist-sqlite-database-to-cache.yml

@@ -14,7 +14,7 @@ jobs:
       PGUSERNAME: upleveled
       PGPASSWORD: upleveled
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: pnpm/action-setup@v4
       - uses: actions/setup-node@v6
         with: