MAINT: update version pins for recent updates (#161)

* update version pins for recent updates

* restore tornado

Author: mmcky

environment.yml

@@ -6,13 +6,12 @@ dependencies:
   - anaconda=2020.11
   - pip
   - pip:
-    - jupyter-book==0.11.2
-    - quantecon-book-theme==0.2.3
+    - jupyter-book==0.11.3
+    - quantecon-book-theme==0.2.7
     - sphinx-tojupyter==0.1.2
     - sphinxext-rediraffe==0.2.7
     - sphinx-exercise==0.1.1
     - ghp-import==1.1.0
-    - jupinx==0.2.3
     # Temporary Fixes
     - tornado>=6.1