build(deps): 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/bandit.yml

@@ -34,7 +34,7 @@ jobs:
       contents: read
       security-events: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - uses: actions/setup-python@v5
         with:

.github/workflows/codeql-analysis.yml

@@ -7,7 +7,7 @@
 # Results appear in the Security → Code scanning tab.
 #
 # Audit notes (2026-03-11):
-#   - actions/checkout@v4 and github/codeql-action@v3 are GitHub first-party
+#   - actions/checkout@v6 and github/codeql-action@v3 are GitHub first-party
 #     actions; mutable tags are acceptable per GitHub's own guidance.
 #   - Python is an interpreted language — Autobuild is effectively a no-op
 #     but is kept for forward-compatibility if compiled extensions are added.
@@ -42,7 +42,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
 
     - name: Initialize CodeQL
       uses: github/codeql-action/init@v3

.github/workflows/pip-audit.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Set up Python
         uses: actions/setup-python@v5

.github/workflows/scorecard.yml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           persist-credentials: false
 

.github/workflows/semgrep.yml

@@ -38,7 +38,7 @@ jobs:
       contents: read
       security-events: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Semgrep scan
         run: semgrep scan --config=auto --sarif -o semgrep.sarif || true