ci: install grcov for coverage

Author: KKould

.github/workflows/ci.yml

@@ -57,7 +57,7 @@ jobs:
         with:
           components: llvm-tools-preview
       - uses: Swatinem/rust-cache@v2
-      - uses: taiki-e/install-action@cargo-llvm-cov
+      - uses: taiki-e/install-action@grcov
 
       - name: Generate Codecov report
         run: make codecov