Update actions/checkout action to v6 (#87)

Author: renovate[bot]

.github/workflows/coverage.yml

@@ -18,7 +18,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
     # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
 
     - name: Install bazelisk
       run: |

.github/workflows/main.yml

@@ -24,7 +24,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
     # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
 
     - name: Install bazelisk
       run: |