Add caching in release builds (#145)

Author: gmorpheme

.github/workflows/build-rust.yaml

@@ -89,6 +89,13 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 0
+      - uses: actions/cache@v1
+        with:
+          path: ~/.cargo
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.toml') }}-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.toml') }}
+            ${{ runner.os }}-cargo
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
@@ -149,6 +156,13 @@ jobs:
     if: github.ref == 'refs/heads/master'
     steps:
       - uses: actions/checkout@v2
+      - uses: actions/cache@v1
+        with:
+          path: ~/.cargo
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.toml') }}-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.toml') }}
+            ${{ runner.os }}-cargo
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal