CI: Bump actions/checkout from 5 to 6 (#1944)

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](https://github.com/actions/checkout/compare/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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/benchmark.yml

@@ -13,11 +13,11 @@ jobs:
 
     steps:
       # check out pull request branch
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           path: pr
       # check out main branch (to compare performance)
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           ref: main
           path: main

.github/workflows/docs.yml

@@ -14,7 +14,7 @@ jobs:
     permissions: {}
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: actions/setup-node@v6
     - run: npm ci --ignore-scripts
     - run: npm run docs

.github/workflows/sop-test-suite.yml

@@ -17,14 +17,14 @@ jobs:
         password: ${{ secrets.github_token }}
     steps:
       # check out repo for scripts
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       # the interop image does not include Node.js
       - uses: actions/setup-node@v6
         with:
           node-version: '22.x'
       # check out pull request branch
       - name: Checkout openpgpjs-branch
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           path: openpgpjs-branch
       - name: Install openpgpjs-branch
@@ -35,7 +35,7 @@ jobs:
           OPENPGPJS_PATH: ${{ github.workspace }}/openpgpjs-branch
       # check out main branch
       - name: Checkout openpgpjs-main
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           ref: main
           path: openpgpjs-main
@@ -78,7 +78,7 @@ jobs:
     permissions: {}
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Download test results json artifact
         id: download-test-results
         uses: actions/download-artifact@v6

.github/workflows/tests.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     permissions: {}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
       - name: Check for cached folders
         id: cache-full
@@ -40,7 +40,7 @@ jobs:
     needs: build
     permissions: {}
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: actions/setup-node@v6
       with:
         node-version: ${{ matrix.node-version }}
@@ -70,7 +70,7 @@ jobs:
     permissions: {}
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
 
       - name: Retrieve cached built folders
@@ -132,7 +132,7 @@ jobs:
       BROWSERSTACK_ACCESS_KEY: VjgBVRMxNVBj7SjJFiau
     
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
 
       - name: Generate self-signed HTTPS certificates for web-test-runner server
@@ -180,7 +180,7 @@ jobs:
     permissions: {}
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: actions/setup-node@v6
     - run: npm ci --ignore-scripts # TS
     - name: Retrieve cached folders
@@ -201,7 +201,7 @@ jobs:
       pull-requests: write # allow comments
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: actions/setup-node@v6
     - run: npm ci --ignore-scripts # linter
     - name: Retrieve cached folders