Bump actions/checkout from 3 to 4 (#141)

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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/build.yml

@@ -21,7 +21,7 @@ jobs:
           access_token: ${{ github.token }}
 
       - name: Checkout Repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Rust 1.64 toolchain
         uses: dtolnay/rust-toolchain@master

.github/workflows/slowtests.yml

@@ -20,7 +20,7 @@ jobs:
           access_token: ${{ github.token }}
 
       - name: Checkout Repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Rust 1.64 toolchain
         uses: dtolnay/rust-toolchain@master