Remove version checks using pipdated.

Patch by Marius Brehler <marbre@linux.sungazer.de>
--- a/matplotlib2tikz/__init__.py
+++ b/matplotlib2tikz/__init__.py
@@ -15,9 +15,3 @@ from matplotlib2tikz.__about__ import (
         )
 
 from matplotlib2tikz.save import save
-
-import pipdated
-if pipdated.needs_checking('matplotlib2tikz'):
-    msg = pipdated.check('matplotlib2tikz', __version__)
-    if msg:
-        print(msg)