ci: bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...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/aeon_ci.yml

@@ -1,4 +1,4 @@
-name: Aeon CI
+name: Aeon CI
 
 on:
   push:
@@ -11,7 +11,7 @@ jobs:
     name: Code Analysis
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install cppcheck
         run: sudo apt-get install -y cppcheck
       - name: Run cppcheck on Aeon headers
@@ -26,7 +26,7 @@ jobs:
     name: Sovereign Integrity Check
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: No private keys or tokens in source
         run: |
           if grep -rE "BEGIN.*(PRIVATE|RSA|EC) KEY|ghp_|ghs_|glpat-" --include="*.h" --include="*.cpp" --include="*.py" . 2>/dev/null; then
@@ -42,7 +42,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: softprops/action-gh-release@v2
         with:
           generate_release_notes: true

.github/workflows/deploy_evolution.yml

@@ -21,7 +21,7 @@ jobs:
       id-token: write
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Authenticate to Google Cloud
         uses: google-github-actions/auth@v2