build(deps): bump actions/checkout from 4 to 5

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/validate.yml

@@ -30,7 +30,7 @@ jobs:
   lint:
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: actions/setup-go@v5
         with:
           go-version: 1.24.x
@@ -41,7 +41,7 @@ jobs:
   codespell:
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v5
     - name: install deps
       # Version of codespell bundled with Ubuntu is way old, so use pip.
       run: pip install codespell
@@ -51,14 +51,14 @@ jobs:
   cross:
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: cross
         run: make build-cross
 
   test-stubs:
     runs-on: macos-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: actions/setup-go@v5
         with:
           go-version: 1.24.x
@@ -76,7 +76,7 @@ jobs:
         race: ["-race", ""]
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: install go ${{ matrix.go-version }}
         uses: actions/setup-go@v5
@@ -101,7 +101,7 @@ jobs:
           - template://experimental/opensuse-tumbleweed
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: "Install Lima"
         uses: lima-vm/lima-actions/setup@v1