Bump actions/checkout from 2 to 4

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] <[email protected]>

.github/workflows/main.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
 
     - name: Build tests
       run: |
@@ -22,7 +22,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
 
     - name: Build tests
       run: docker buildx build . --target test-clang -t spectrum:tests-clang
@@ -32,7 +32,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
 
     - name: Build tests
       run: docker buildx build . --target test-musl -t spectrum:tests-musl
@@ -41,7 +41,7 @@ jobs:
   macos:
     runs-on: macos-14
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Install MacPorts
       run: |
         curl -L -O "https://github.com/macports/macports-base/releases/download/v2.9.0/MacPorts-2.9.0-14-Sonoma.pkg"
@@ -70,7 +70,7 @@ jobs:
   windows:
     runs-on: windows-2022
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         curl -L -O https://packages.spectrum.im/deps32.zip

.github/workflows/publish.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-20.04
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Docker meta
       id: docker_meta
       uses: crazy-max/ghaction-docker-meta@v5