Update required JupyterLab version to 4.5

We need that version because it adds support for custom content providers, something our extension depends on:
https://jupyterlab.readthedocs.io/en/stable/extension/extension_points.html#content-provisioning

Signed-off-by: Andy Jakubowski <[email protected]>

Author: andyjakubowski

README.md

@@ -8,7 +8,7 @@ Read‑only viewer for Deepnote `.deepnote` files inside JupyterLab.
 ## Requirements
 
 - Python 3.9 or higher
-- JupyterLab 4.0.0 or higher
+- JupyterLab 4.5.0 or higher
 
 ## Install