chore(deps): bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/lint.yml

@@ -17,7 +17,7 @@ jobs:
         with:
           go-version: 1.23
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v8

.github/workflows/proto-registry.yaml

@@ -12,7 +12,7 @@ jobs:
   push:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: bufbuild/[email protected]
       - uses: bufbuild/buf-push-action@v1
         with: