Switch to codecov action v5+ for tokenless uploads

Author: taylanisikdemir

.github/workflows/codecov.yml

@@ -23,9 +23,8 @@ jobs:
         run: make cover_profile
 
       - name: Upload coverage reports to Codecov
-        uses: codecov/codecov-action@v4.5.0 # https://github.com/codecov/codecov-action
+        uses: codecov/codecov-action@v5.0.7 # https://github.com/codecov/codecov-action
         with:
           file: .build/coverage/unit_cover.out
           exclude: ./
-          token: ${{ secrets.CODECOV_TOKEN }}
           slug: cadence-workflow/cadence