Upgrade quantecon-book-theme to v0.13.0 - collapsible stderr warnings (#733)

* test: Install theme from PR #333 branch for collapsible stderr warnings feature

* Update to released quantecon-book-theme v0.13.0 from PyPI

Author: mmcky

environment.yml

@@ -7,7 +7,7 @@ dependencies:
   - pip
   - pip:
     - jupyter-book==1.0.4post1
-    - quantecon-book-theme==0.12.0
+    - quantecon-book-theme==0.13.0
     - sphinx-tojupyter==0.4.0
     - sphinxext-rediraffe==0.2.7
     - sphinx-exercise==1.2.0