chore(deps): update actions/checkout action to v6

| datasource  | package          | from | to |
| ----------- | ---------------- | ---- | -- |
| github-tags | actions/checkout | v5   | v6 |


Signed-off-by: renovate-sh-app[bot] <219655108+renovate-sh-app[bot]@users.noreply.github.com>

Author: renovate-sh-app[bot]

.github/workflows/lint.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
         with:
           persist-credentials: false
       - name: Setup go

.github/workflows/release.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
         with:
           fetch-depth: 0
           persist-credentials: false

.github/workflows/sync-k6-deps.yaml

@@ -16,7 +16,7 @@ jobs:
       GH_TOKEN: ${{ github.token }}
       BRANCH_NAME: ci-sync-deps
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
         with:
           fetch-depth: 0
           token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/test.yml

@@ -33,7 +33,7 @@ jobs:
           go-version: "1.24.x"
           cache: false
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
         with:
           persist-credentials: false