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] <support@github.com>

.github/workflows/build.yaml

@@ -14,7 +14,7 @@ jobs:
         package: ["realadsb", "fr24", "piaware", "planefinder", "tcllauncher"]
     steps:
       - name: Checkout flake
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install nix
         uses: DeterminateSystems/nix-installer-action@v4

.github/workflows/flake-checker.yaml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout flake
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install nix
         uses: DeterminateSystems/nix-installer-action@v4

.github/workflows/lock-updater.yaml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout flake
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install nix
         uses: DeterminateSystems/nix-installer-action@v4