Update to codecov-action@v3

Author: GDYendell

.github/workflows/code.yml

@@ -106,7 +106,7 @@ jobs:
         run: twine upload dist/*
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v3
         with:
           name: ${{ matrix.os }}/${{ matrix.python }}/${{ matrix.epics }}
           files: cov.xml