Bump actions/checkout from 2.3.5 to 2.4.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.5 to 2.4.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2.3.5...v2.4.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/release.yml

@@ -42,7 +42,7 @@ jobs:
       - name: Read Swift Version
         uses: sersoft-gmbh/swift-version-action@v1.0.0
         id: swift-version
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
       - uses: actions/cache@v2.1.6
         with:
           path: .build

.github/workflows/swift-test.yml

@@ -33,7 +33,7 @@ jobs:
       - name: Read Swift Version
         uses: sersoft-gmbh/swift-version-action@v1.0.0
         id: swift-version
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
       - uses: actions/cache@v2.1.6
         with:
           path: .build
@@ -75,7 +75,7 @@ jobs:
       - uses: maxim-lobanov/setup-xcode@v1.4.0
         with:
           xcode-version: ^12.4
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
       - uses: sersoft-gmbh/xcodebuild-action@v1.8.0
         with:
           spm-package: './'