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](https://github.com/actions/checkout/compare/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.yml

@@ -8,7 +8,7 @@ jobs:
   build-custom-packages:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: DeterminateSystems/magic-nix-cache-action@v2
       - uses: DeterminateSystems/nix-installer-action@v4
         with:

.github/workflows/check.yml

@@ -11,7 +11,7 @@ jobs:
   check-outputs:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: DeterminateSystems/nix-installer-action@v4
       - name: Check flake lockfile
         uses: DeterminateSystems/flake-checker-action@v5

.github/workflows/flakehub-push.yml

@@ -10,7 +10,7 @@ jobs:
       id-token: "write"
       contents: "read"
     steps:
-      - uses: "actions/checkout@v3"
+      - uses: "actions/checkout@v4"
       - uses: "DeterminateSystems/nix-installer-action@main"
       - uses: "DeterminateSystems/flakehub-push@main"
         with:

.github/workflows/iso.yml

@@ -13,7 +13,7 @@ jobs:
           - "x86_64-linux"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: DeterminateSystems/magic-nix-cache-action@v2
       - uses: DeterminateSystems/nix-installer-action@v4
       - name: Build ISO

.github/workflows/site.yml

@@ -8,7 +8,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: DeterminateSystems/magic-nix-cache-action@v2
       - uses: DeterminateSystems/nix-installer-action@v4
       - env:

.github/workflows/update-firefox-addons.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Set the date
         id: metadata
         run: echo "DATE=$(date +%F)" >> "$GITHUB_OUTPUT"
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: DeterminateSystems/nix-installer-action@v4
       - env:
           NIXPKGS_ALLOW_UNFREE: "1"

.github/workflows/update.yml

@@ -12,7 +12,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: DeterminateSystems/nix-installer-action@v4
       - name: Update flake inputs
         run: |