Bump actions/checkout from 3 to 4 (#525)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  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/CompatHelper.yml

@@ -9,7 +9,7 @@ jobs:
   CompatHelper:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Get Julia compatibility
         id: julia_compat
         # NOTE: this requires a Julia compat lower-bound with minor version!

.github/workflows/ManifestUpdater.yml

@@ -9,7 +9,7 @@ jobs:
   ManifestUpdater:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Get Julia compatibility
         id: julia_compat
         # NOTE: this requires a julia compat lower-bound with minor version!

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         os: [ubuntu-latest, macOS-latest, windows-latest]
         arch: [x64]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v1
         with:
           version: ${{ matrix.version }}
@@ -70,8 +70,8 @@ jobs:
             os: 'windows-latest'
             arch: 'x64'
     steps:
-      - uses: actions/checkout@v3
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
+      - uses: actions/checkout@v4
         with:
           repository: 'JuliaLang/julia'
           ref: ${{ matrix.branch }}