Bump actions/checkout from 2 to 4 (#595)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...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>

.github/workflows/CI.yml

@@ -28,7 +28,7 @@ jobs:
           - os: macOS-latest
             arch: x86
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}

.github/workflows/IntegrationTest.yml

@@ -19,7 +19,7 @@ jobs:
           - {user: timholy, repo: SnoopCompile.jl}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.julia-version }}
@@ -29,7 +29,7 @@ jobs:
         run: 'using Pkg; Pkg.develop(path=joinpath(pwd(), "TypedSyntax"))'
       - uses: julia-actions/julia-buildpkg@latest
       - name: Clone Downstream
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           repository: ${{ matrix.package.user }}/${{ matrix.package.repo }}
           path: downstream

.github/workflows/TypedSyntaxCI.yml

@@ -23,7 +23,7 @@ jobs:
           - x64
           - x86
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}