[gh actions] Invalidate cargo-registry cache

.github/workflows/main.yml

@@ -30,7 +30,7 @@ jobs:
       uses: actions/cache@v1
       with:
         path: ~/.cargo/registry
-        key: ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}
+        key: ${{ runner.os }}-cargo-registry2-${{ hashFiles('**/Cargo.lock') }}
 
     - name: Cache cargo index
       uses: actions/cache@v1