Fix cargo audit caching

See
https://github.com/actions/cache/issues/133#issuecomment-599102035
for chown bit

.github/workflows/ci.yaml

@@ -29,9 +29,10 @@ jobs:
     - name: Cache cargo
       uses: actions/cache@v1
       with:
-        path: ~/.cargo
+        path: ~/.cargo/
         key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
 
+    - run: sudo chown -R $(whoami):$(id -ng) ~/.cargo/
     - run: cargo install cargo-audit
     - run: cargo audit