bring back Rust cache with tuning

Author: georgeh0

.github/workflows/_test.yml

@@ -43,6 +43,14 @@ jobs:
 
         - run: rustup toolchain install stable --profile minimal
 
+        - name: Rust Cache
+          uses: Swatinem/rust-cache@v2
+          with:
+            key: rust-${{ matrix.platform.runner }}-${{ matrix.python-version }}
+            cache-targets: 'false'
+            cache-all-crates: 'false'
+            cache-workspace-crates: 'false'
+
         - name: Rust tests (no default features)
           run: cargo test --no-default-features --verbose