chore(deps): bump actions/checkout from 5 to 6 in the actions group

Bumps the actions group with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `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
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/branch-sync.yml

@@ -11,7 +11,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout main
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Push updates to master
         uses: ad-m/github-push-action@master

.github/workflows/cd.yml

@@ -14,7 +14,7 @@ jobs:
   dist:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
 

.github/workflows/ci-pages.yml

@@ -23,7 +23,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
 

.github/workflows/ci.yml

@@ -33,7 +33,7 @@ jobs:
             python-version: "3.9"
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Setup uv
         uses: astral-sh/setup-uv@v7

.github/workflows/ci_latex.yml

@@ -45,7 +45,7 @@ jobs:
         python-version: ['3.12']
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Setup uv
         uses: astral-sh/setup-uv@v7

.github/workflows/head-dependencies.yml

@@ -16,7 +16,7 @@ jobs:
         python-version: ['3.12']
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
 
     - uses: astral-sh/setup-uv@v7
       with:
@@ -64,7 +64,7 @@ jobs:
         python-version: ['3.12']
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
 
     - uses: astral-sh/setup-uv@v7
       with:
@@ -118,7 +118,7 @@ jobs:
         python-version: ['3.12']
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
 
     - uses: astral-sh/setup-uv@v7
       with:
@@ -168,7 +168,7 @@ jobs:
         python-version: ['3.12']
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
 
     - uses: astral-sh/setup-uv@v7
       with: