build(deps): bump actions/checkout from 6 to 7

Bumps [actions/checkout](https://github.com/actions/checkout) from 6 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v6...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/deploy-doc.yml

@@ -21,7 +21,7 @@ jobs:
       CXX: g++
       CXXFLAGS: -fdiagnostics-color -O2
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
 
       - name: Install system dependencies
         run: |

.github/workflows/doc-pr-cleanup.yml

@@ -21,7 +21,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout gh-pages branch
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           ref: gh-pages
       - name: Delete preview and history + push changes

.github/workflows/docs-pr-build.yml

@@ -22,7 +22,7 @@ jobs:
       CXX: g++
       CXXFLAGS: -fdiagnostics-color -O2
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
 
       - name: Install system dependencies
         run: |

.github/workflows/format.yml

@@ -9,7 +9,7 @@ jobs:
   check-formatting:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: julia-actions/setup-julia@v3
         with:
           version: "1"

.github/workflows/test.yml

@@ -40,7 +40,7 @@ jobs:
             }
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
 
         # Setup Julia
       - uses: julia-actions/setup-julia@v3