gha: submit codecov on linux only

Author: nschloe

.github/workflows/ci.yml

@@ -26,9 +26,9 @@ jobs:
         python-version: ["3.7", "3.8", "3.9", "3.10"]
         include:
           - platform: macos-latest
-            python-version: "3.9"
+            python-version: "3.10"
           - platform: windows-latest
-            python-version: "3.9"
+            python-version: "3.10"
 
     runs-on: ${{ matrix.platform }}
 
@@ -42,4 +42,4 @@ jobs:
           pip install tox
           tox -- --cov pytest_codeblocks --cov-report xml --cov-report term
       - uses: codecov/codecov-action@v1
-        if: ${{ matrix.python-version == '3.9' }}
+        if: ${{ matrix.python-version == '3.10' && matrix.os == 'ubuntu-latest' }}