update_docs.yml: pip install -> pip install -e

I think the problem with the following commands failing
with github actions may come from not having an "editable mode"
installation.

This is a test to see if it works well in github now.

.github/workflows/update_docs.yml

@@ -23,7 +23,7 @@ jobs:
       # Install dependencies for your project
       - name: Install Dependencies
         run: |
-          pip install .[treeview,test,doc]
+          pip install -e .[treeview,test,doc]
 
       # Build Sphinx documentation
       - name: Generate Sphinx Documentation