Use different Codecov flags for GHA_Ubuntu and GHA_macOS

Author: hugovk

.github/workflows/test.yml

@@ -24,6 +24,12 @@ jobs:
           env: PYTHONOPTIMIZE=2
         - python-version: "3.6"
           env: PYTHONOPTIMIZE=1
+        # Include new variables for Codecov
+        - os: ubuntu-latest
+          codecov-flag: GHA_Ubuntu
+        - os: macOS-latest
+          codecov-flag: GHA_macOS
+
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.os }} Python ${{ matrix.python-version }}
 
@@ -97,5 +103,5 @@ jobs:
       uses: codecov/codecov-action@v1
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
-        flags: GHA
+        flags: ${{ matrix.codecov-flag }}
         name: ${{ matrix.os }} Python ${{ matrix.python-version }}