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

Author: renovate[bot]

.github/workflows/test.yml

@@ -21,7 +21,7 @@ jobs:
       id: go
 
     - name: Check out code into the Go module directory
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Test (Unix)
       if: runner.os != 'Windows'