ci: use codecov@v3 (PyMySQL#1142)

methane · web-flow · commit 39bf50e05733 · 2023-11-14T18:34:43.000+09:00
v4 is still beta.
diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
@@ -106,4 +106,4 @@ jobs:
 
       - name: Upload coverage reports to Codecov
         if: github.repository == 'PyMySQL/PyMySQL'
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@v3
