TST: Add skip test to excelwriter contextmanager
Fixes #5094.

Side note - reverting #5058 not because of what version should be xlrd base, but rather because multiple places need to be changed to test with older version of xlrd and we should just go with one min version for xlrd.
 And here's where it was decided to require 0.9 - #1629 . Apparently had to do with Python 3 support? 
