🔧 Configure docs extras dependencies correctly

Turns out groups and extras can't be used together in pyproject.toml by poetry, see python-poetry/poetry#4897. Changed things around so that `pip install .[docs]` works!

Author: weiji14

.github/workflows/deploy-docs.yml

@@ -36,7 +36,7 @@ jobs:
     # Install dependencies needed for documentation build
     - name: Install docs build dependencies
       run: |
-        pip install . jupyter-book planetary-computer pystac
+        pip install .[docs]
         pip list
 
     # Build the docs