chore(ci): cache cargo dependencies

.github/workflows/ci.yml

@@ -40,6 +40,17 @@ jobs:
           profile: minimal
           override: true
 
+      - name: Cache Cargo dependencies
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/
+          key: ${{ runner.os }}-cargo-${{ hashFiles('Cargo.lock') }}
+
       - name: Build
         uses: actions-rs/cargo@v1
         with: