remove token from codecov upload; not required for public repo (#1192)

Author: Joe Bowman

.github/workflows/buildtest.yaml

@@ -104,7 +104,6 @@ jobs:
       - name: Upload coverage reports to Codecov with GitHub Action
         uses: codecov/codecov-action@v4
         with:
-          token: ${{ secrets.CODECOV_TOKEN }} # needed for private repo
           files: ./coverage.txt
           flags: unittests
           fail_ci_if_error: true