not available on conda forge just yet so >= it is

Leah Wasser · web-flow · commit 994df876a4d2 · 2020-01-14T19:12:50.000-07:00
diff --git a/environment.yml b/environment.yml
@@ -44,6 +44,6 @@ dependencies:
   - jupyter_contrib_nbextensions
   - nbclean
   # Autograding
-  - matplotcheck=0.1.1
+  - matplotcheck>=0.1
   - nbgrader
 
