cache builds (#49)

* cache builds

* improve cache steps

* un-restrict target cache

* remove release cache

.github/workflows/rust.yml

@@ -22,6 +22,14 @@ jobs:
           toolchain: stable
           override: true
 
+    - uses: actions/cache@v2
+      with:
+        path: |
+          ~/.cargo/registry
+          ~/.cargo/git
+          target
+        key: ${{ runner.os }}-cargo-release-${{ hashFiles('**/Cargo.lock') }}
+
     - name: Run cargo build
       run: cargo build --all --release && strip target/release/atuin
 
@@ -37,6 +45,14 @@ jobs:
           toolchain: stable
           override: true
 
+    - uses: actions/cache@v2
+      with:
+        path: |
+          ~/.cargo/registry
+          ~/.cargo/git
+          target
+        key: ${{ runner.os }}-cargo-debug-${{ hashFiles('**/Cargo.lock') }}
+
     - name: Run cargo test
       run: cargo test --workspace
 
@@ -53,6 +69,14 @@ jobs:
           override: true
           components: clippy
 
+    - uses: actions/cache@v2
+      with:
+        path: |
+          ~/.cargo/registry
+          ~/.cargo/git
+          target
+        key: ${{ runner.os }}-cargo-debug-${{ hashFiles('**/Cargo.lock') }}
+
     - name: Run clippy
       run: cargo clippy -- -D warnings