fix coveralls flag-name

Author: zariiii9003

.github/workflows/ci.yml

@@ -51,7 +51,7 @@ jobs:
       uses: coverallsapp/github-action@v2
       with:
         github-token: ${{ secrets.github_token }}
-        flag-name: Unittests-${{ matrix.os }}-${{ matrix.python-version }}
+        flag-name: Unittests-${{ matrix.os }}-${{ matrix.env }}
         parallel: true
         path-to-lcov: ./coverage.lcov