tst: updates to sphinx-exercise

Author: mmcky

environment.yml

@@ -11,7 +11,7 @@ dependencies:
     - git+https://github.com/QuantEcon/quantecon-book-theme@maint-22oct
     - sphinx-tojupyter==0.3.0
     - sphinxext-rediraffe==0.2.7
-    - sphinx-exercise==0.4.1
+    - git+https://github.com/executablebooks/sphinx-exercise@maint-22oct
     - ghp-import==2.1.0
     - sphinxcontrib-youtube==1.4.1
     - sphinx-togglebutton==0.3.2