ci: cache go modules in race workflow

.github/workflows/race.yml

@@ -24,6 +24,16 @@ jobs:
         with:
           go-version: ${{ matrix.go-version }}
 
+      - name: Cache Go modules
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+
       - name: Install build tools (for cgo / race detector)
         run: |
           sudo apt-get update