Cache cargo dependencies (#45)

.github/workflows/general.yml

@@ -30,6 +30,15 @@ jobs:
           - 5432:5432
     steps:
       - uses: actions/checkout@v2
+      - name: Cache dependencies
+        id: cache-dependencies
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal