Cache dependencies in CI

.github/workflows/check.yaml

@@ -39,6 +39,15 @@ jobs:
       - name: Checkout the code
         uses: actions/checkout@v2
 
+      - name: Setup Cargo cache
+        uses: actions/cache@v2.1.5
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: cargo-${{ hashFiles('**/Cargo.lock') }}-clippy
+
       - name: Install toolchain
         uses: actions-rs/toolchain@v1
         with:
@@ -78,6 +87,15 @@ jobs:
       - name: Checkout the code
         uses: actions/checkout@v2
 
+      - name: Setup Cargo cache
+        uses: actions/cache@v2.1.5
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}-${{ matrix.os.target }}-${{ matrix.toolchain }}
+
       - name: Install toolchain
         uses: actions-rs/toolchain@v1
         with: