Enable caching of the registry

Author: ithinuel

.github/workflows/build_and_test.yml

@@ -48,6 +48,15 @@ jobs:
           target: thumbv6m-none-eabi
           override: true
           profile: minimal
+      - name: Enable cache
+        uses: actions/cache@v3
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+          key: ${{ runner.os }}-cargo
       - name: Check unused deps
         uses: aig787/cargo-udeps-action@v1
         with: