Add back quantecon install

Author: HumphreyYang

lectures/lake_model.md

@@ -29,7 +29,14 @@ kernelspec:
 :depth: 2
 ```
 
-+++
+In addition to what's in Anaconda, this lecture will need the following libraries:
+
+```{code-cell} ipython
+---
+tags: [hide-output]
+---
+!pip install quantecon
+```
 
 ## Overview