Enable cache in GH actions

.github/workflows/ci.yml

@@ -21,6 +21,13 @@ jobs:
         with:
           toolchain: ${{ matrix.rust }}
           components: rustfmt
+      - uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            target/
+          key: cargo-${{ runner.os }}-${{ matrix.name }}-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: cargo-${{ runner.os }}-R${{ matrix.rust }}-
       - name: Build
         run: cargo build ${{ matrix.cargo_args }}
         env:
@@ -48,6 +55,13 @@ jobs:
         with:
           toolchain: nightly
           components: llvm-tools-preview
+      - uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            target/
+          key: cargo-${{ runner.os }}-Coverage-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: cargo-${{ runner.os }}-Rnightly-
       - name: Test
         run: cargo test --features coverage
         env: