Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...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/buf-ci.yaml

@@ -20,7 +20,7 @@ jobs:
     if: ${{ github.event_name != 'pull_request' || github.head_ref != 'fetch-modules' }}
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: bufbuild/buf-action@v1
         with:
           token: ${{ secrets.BUF_TOKEN }}

.github/workflows/ci.yaml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 1
       - name: Install Go

.github/workflows/fetch.yaml

@@ -23,7 +23,7 @@ jobs:
           permission-pull-requests: write
           permission-members: read
       - name: Checkout repository code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install Go
         uses: actions/setup-go@v6
         with:

.github/workflows/release.yaml

@@ -21,7 +21,7 @@ jobs:
       did_release: ${{ steps.release.outputs.did_release }}
     steps:
       - name: Checkout repository code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install Go
         uses: actions/setup-go@v6
         with:
@@ -66,7 +66,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install Go
         uses: actions/setup-go@v6
         with: