build(deps): bump actions/checkout from 3 to 4

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]>

.github/workflows/integration.yml

@@ -19,7 +19,7 @@ jobs:
     steps:
 
     - name: Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Setup LXD
       uses: ./

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
     steps:
 
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup LXD
         uses: ./
@@ -25,7 +25,7 @@ jobs:
     steps:
 
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup LXD
         uses: ./
@@ -48,7 +48,7 @@ jobs:
     steps:
 
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup LXD
         uses: ./