update GitHub Actions workflow to trigger on pull requests to main and fix output path for coverage report

.github/workflows/run_tests.yml

@@ -1,12 +1,16 @@
 name: Tests and Coverage
 
-on: [pull_request, push]
+on:
+  pull_request:
+    branches:
+      - main
 
 jobs:
   coverage:
     runs-on: ubuntu-latest
     env:
       CARGO_TERM_COLOR: always
+
     steps:
       - uses: actions/checkout@v4
       - name: Install Rust
@@ -14,10 +18,10 @@ jobs:
       - name: Install cargo-llvm-cov
         uses: taiki-e/install-action@cargo-llvm-cov
       - name: Generate code coverage
-        run: cargo llvm-cov --all-features --workspace --lcov --output-path lcov.info
+        run: cargo llvm-cov --all-features --workspace --lcov --output-path lcov.infoa
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v3
         with:
-          token: ${{ secrets.CODECOV_TOKEN }} # not required for public repos
+          token: ${{ secrets.CODECOV_TOKEN }}
           files: lcov.info
-          fail_ci_if_error: true
+          fail_ci_if_error: true