Bump actions/checkout from 3.6.0 to 4.0.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 3.6.0 to 4.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3.6.0...v4.0.0)

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

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

.github/workflows/Downstream.yml

@@ -30,14 +30,14 @@ jobs:
           - {user: SciML, repo: OperatorLearning.jl, group: All}
     if: contains(github.event.pull_request.labels.*.name, 'run downstream test')
     steps:
-      - uses: actions/checkout@v3.6.0
+      - uses: actions/checkout@v4.0.0
       - uses: julia-actions/setup-julia@v1
         with:
           version: ${{ matrix.julia-version }}
           arch: x64
       - uses: julia-actions/julia-buildpkg@latest
       - name: Clone Downstream
-        uses: actions/checkout@v3.6.0
+        uses: actions/checkout@v4.0.0
         with:
           repository: ${{ matrix.package.user }}/${{ matrix.package.repo }}
           path: downstream

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
             version: '1'
             arch: x64
     steps:
-      - uses: actions/checkout@v3.6.0
+      - uses: actions/checkout@v4.0.0
       - uses: julia-actions/setup-julia@v1
         with:
           version: ${{ matrix.version }}
@@ -65,7 +65,7 @@ jobs:
     name: Documentation
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3.6.0
+      - uses: actions/checkout@v4.0.0
       - uses: julia-actions/setup-julia@v1
         with:
           version: '1'

.github/workflows/clean_preview.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout gh-pages branch
-        uses: actions/checkout@v3.6.0
+        uses: actions/checkout@v4.0.0
         with:
           ref: gh-pages
       - name: Delete preview and history + push changes

.github/workflows/fluxbot.yml

@@ -14,7 +14,7 @@ jobs:
         julia-arch: [x86]
         os: [ubuntu-latest]
     steps:
-      - uses: actions/checkout@v3.6.0 # v1.0.0
+      - uses: actions/checkout@v4.0.0 # v1.0.0
       - uses: julia-actions/setup-julia@v1
         with:
           version: ${{ matrix.julia-version }}

.github/workflows/nightly-ci.yml

@@ -20,7 +20,7 @@ jobs:
         os: [ubuntu-latest]
         arch: [x64]
     steps:
-      - uses: actions/checkout@v3.6.0
+      - uses: actions/checkout@v4.0.0
       - uses: julia-actions/setup-julia@v1
         with:
           version: ${{ matrix.version }}