Use underscores to separate CI and platform

Author: hugovk

.github/workflows/test-docker.yml

@@ -66,5 +66,5 @@ jobs:
       uses: codecov/codecov-action@v1
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
-        flags: GHADocker
+        flags: GHA_Docker
         name: ${{ matrix.docker }}

.github/workflows/test-windows.yml

@@ -361,7 +361,7 @@ jobs:
       with:
           token: ${{ secrets.CODECOV_TOKEN }}
           file: ./coverage.xml
-          flags: GHAWindows
+          flags: GHA_Windows
           name: ${{ runner.os }} Python ${{ matrix.python-version }}
 
     - name: Build wheel