ci: checkout first, disable go caching

.github/workflows/test.yml

@@ -11,12 +11,16 @@ jobs:
       run:
         shell: bash
     steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
     - name: Install Go
       uses: actions/setup-go@v5
       with:
         go-version: ${{ matrix.go-version }}
-    - name: Checkout code
-      uses: actions/checkout@v4
+        # Disable caching as we don't have top-level go.sum needed for
+        # the cache key, and specifying multiple go.sums is not trivial
+        # (see https://github.com/moby/sys/pull/160 for details).
+        cache: false
     - name: Set PACKAGES env
       if: ${{ matrix.go-version == '1.18.x' }}
       run: |