fix: update Codecov badge to include authentication token

Author: devin-ai-integration[bot]

README.md

@@ -1,7 +1,7 @@
 # jupyterlab_deepnote
 
 [![CI](https://github.com/deepnote/jupyterlab-deepnote/actions/workflows/build.yml/badge.svg?branch=main)](https://github.com/deepnote/jupyterlab-deepnote/actions/workflows/build.yml)
-[![codecov](https://codecov.io/gh/deepnote/jupyterlab-deepnote/branch/main/graph/badge.svg)](https://codecov.io/gh/deepnote/jupyterlab-deepnote)
+[![codecov](https://codecov.io/gh/deepnote/jupyterlab-deepnote/graph/badge.svg?token=OV32VZNOJ2)](https://codecov.io/gh/deepnote/jupyterlab-deepnote)
 
 A Deepnote extension for JupyterLab