Fix bumpversion config

Author: dstansby

.bumpversion.cfg

@@ -9,10 +9,6 @@ replace = __version__ == '{new_version}'
 search = Matplotlib {current_version}
 replace = Matplotlib {new_version}
 
-[bumpversion:file:./Makefile]
-search = v{current_version}
-replace = v{new_version}
-
 [bumpversion:file:./cheatsheets.tex]
 search = Version {current_version}
 replace = Version {new_version}