Upgrade back to 8.2 now that it as been fixed

Author: nthiery

Dockerfile

@@ -1,7 +1,7 @@
 # Dockerfile for binder
 # Reference: https://mybinder.readthedocs.io/en/latest/dockerfile.html#preparing-your-dockerfile
 
-FROM sagemath/sagemath:8.1
+FROM sagemath/sagemath:8.2
 
 # Copy the contents of the repo in ${HOME}
 COPY --chown=sage:sage . ${HOME}