Remove `codecov (#1391)

Author: jakirkham

.github/workflows/python-package.yml

@@ -58,7 +58,7 @@ jobs:
       run: |
         conda activate zarr-env
         python -m pip install --upgrade pip
-        python -m pip install -U pip setuptools wheel codecov line_profiler
+        python -m pip install -U pip setuptools wheel line_profiler
         python -m pip install -rrequirements_dev_minimal.txt numpy${{matrix.numpy_version}} -rrequirements_dev_optional.txt pymongo redis
         python -m pip install .
         python -m pip freeze