Update environment to remove non-build packages (#159)

Author: mmcky

environment.yml

@@ -16,13 +16,11 @@ dependencies:
     - ghp-import==1.1.0
     - sphinxcontrib-youtube==1.1.0
     - sphinx-togglebutton==0.3.1
-    - quantecon
-    - array-to-latex
-    - prettytable
-    - graphviz
     # Sandpit Requirements
     # - PuLP
     # - cvxpy
     # - cvxopt
     # - cylp
+    # - array-to-latex
+    # - prettytable