.github/workflows: use cache to speed up Windows tests

Fixes #872

Signed-off-by: Alex Brainman <alex.brainman@gmail.com>

.github/workflows/windows.yml

@@ -24,6 +24,14 @@ jobs:
     - name: Checkout code
       uses: actions/checkout@v2
 
+    - name: Restore Cache
+      uses: actions/cache@v2
+      with:
+        path: ~/go/pkg/mod
+        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-go-
+
     - name: Test
       run: go test ./...