Bump actions/checkout from 5 to 6 (#2850)

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](actions/checkout@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>

Author: dependabot[bot]

.github/workflows/CI.yml

@@ -44,7 +44,7 @@ jobs:
             version: '1.6'
             arch: default
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
@@ -78,7 +78,7 @@ jobs:
           - ubuntu-latest
           - windows-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: "Download and install DejaVu fonts"
         run: |
           Invoke-WebRequest "https://github.com/dejavu-fonts/dejavu-fonts/releases/download/version_2_37/dejavu-fonts-ttf-2.37.zip" -OutFile "DejaVu.zip"
@@ -142,7 +142,7 @@ jobs:
     name: "CSS for HTML themes"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1'
@@ -162,7 +162,7 @@ jobs:
           - windows-latest
           - ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1'
@@ -199,7 +199,7 @@ jobs:
           - html
           - pdf
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1'
@@ -229,7 +229,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: docs
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: 1
@@ -264,7 +264,7 @@ jobs:
     permissions:
       contents: read
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@latest
         with:
           version: '1'
@@ -294,7 +294,7 @@ jobs:
     name: "Linkcheck: Documenter manual"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@latest
         with:
           version: '1'
@@ -309,7 +309,7 @@ jobs:
     name: Prettier (JS code formatting)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actionsx/prettier@v3
         with:
           args: --check .
@@ -318,7 +318,7 @@ jobs:
     name: "Runic (Julia code formatting)"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1.11'
@@ -332,7 +332,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Actions Repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Check spelling
         uses: crate-ci/typos@master
 

.github/workflows/ClearPreview.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout gh-pages branch
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           ref: gh-pages
       - name: Delete preview and history + push changes

.github/workflows/regression-tests.yml

@@ -31,7 +31,7 @@ jobs:
           - package: 'DocumenterDescriptions'
           - package: 'DocumenterVitepress'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1'
@@ -55,7 +55,7 @@ jobs:
           - package: 'MathOptInterface'
           - package: 'Oscar'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1'
@@ -87,7 +87,7 @@ jobs:
     name: "Julia Manual"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: 'nightly'