Test quantecon-book-theme PR #330: fix streaming output whitespace

Install quantecon-book-theme from the fix-streaming-output-whitespace branch
to test the CSS fix for excessive whitespace between consecutive streaming
output lines in Jupyter code cells.

Related: QuantEcon/quantecon-book-theme#330

Author: claude

environment.yml

@@ -7,7 +7,7 @@ dependencies:
   - pip
   - pip:
     - jupyter-book==1.0.4post1
-    - quantecon-book-theme==0.11.0
+    - git+https://github.com/QuantEcon/quantecon-book-theme.git@fix-streaming-output-whitespace
     - sphinx-tojupyter==0.4.0
     - sphinxext-rediraffe==0.2.7
     - sphinx-exercise==1.2.0