Update source code link in Quarto config (#135)

Changed the GitHub source code link in _quarto.yml to point directly to the pkg-py directory in the repository for improved navigation.

Author: karangattu

pkg-py/docs/_quarto.yml

@@ -34,7 +34,7 @@ website:
       - icon: github
         menu:
           - text: Source code
-            href:  https://github.com/posit-dev/shinychat/pkg-py
+            href:  https://github.com/posit-dev/shinychat/tree/main/pkg-py
           - text: Report a bug
             href:  https://github.com/posit-dev/shinychat/issues/new