Add MambuPy to the list of projects pledging to drop python2 support.

Author: jstitch

_sections/30-projects.md

@@ -73,6 +73,7 @@ for some that aren't directly comparable. -->
 - [tinytext](https://github.com/hugovk/tinytext)
 - [OSMViz](https://github.com/hugovk/osmviz)
 - [fino](https://github.com/hugovk/fino)
+  [MambuPy](https://github.com/jstitch/MambuPy)
 
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