CI: Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/dev-container.yml

@@ -22,7 +22,7 @@ jobs:
     steps:
 
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3

.github/workflows/label-pull-requests.yml

@@ -15,7 +15,7 @@ jobs:
     if: always() && github.repository == 'SerenityOS/serenity'
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Label pull request
         uses: actions/github-script@v8

.github/workflows/lagom-template.yml

@@ -31,10 +31,10 @@ jobs:
       # Pull requests can trail behind `master` and can cause breakage if merging before running the CI checks on an updated branch.
       # Luckily, GitHub creates and maintains a merge branch that is updated whenever the target or source branch is modified. By
       # checking this branch out, we gain a stabler `master` at the cost of reproducibility.
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         if: ${{ github.event_name != 'pull_request' }}
 
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         if: ${{ github.event_name == 'pull_request' }}
         with:
           ref: refs/pull/${{ github.event.pull_request.number }}/merge

.github/workflows/manpages.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-24.04
     if: always() && github.repository == 'SerenityOS/serenity' && github.ref == 'refs/heads/master'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: r-lib/actions/setup-pandoc@v2
         with:
           pandoc-version: '2.13'

.github/workflows/serenity-template.yml

@@ -36,10 +36,10 @@ jobs:
       # Pull requests can trail behind `master` and can cause breakage if merging before running the CI checks on an updated branch.
       # Luckily, GitHub creates and maintains a merge branch that is updated whenever the target or source branch is modified. By
       # checking this branch out, we gain a stabler `master` at the cost of reproducibility.
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         if: ${{ github.event_name != 'pull_request' }}
 
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         if: ${{ github.event_name == 'pull_request' }}
         with:
           ref: refs/pull/${{ github.event.pull_request.number }}/merge

.github/workflows/social-media.yml

@@ -8,7 +8,7 @@ jobs:
     if: always() && github.repository == 'SerenityOS/serenity' && github.ref == 'refs/heads/master'
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version: '14'
@@ -28,7 +28,7 @@ jobs:
     if: always() && github.repository == 'SerenityOS/serenity' && github.ref == 'refs/heads/master'
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version: '14'

.github/workflows/wasm.yml

@@ -15,10 +15,10 @@ jobs:
       fail-fast: false
     steps:
       - name: Checkout SerenityOS/serenity
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Checkout SerenityOS/libjs-data libjs-wasm
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: SerenityOS/libjs-data
           path: libjs-data