Update the 'Become a Patron' badge

The badge conforms to new branding of patreon.com and is taken from the
official media kit

README.md

@@ -30,7 +30,7 @@ If you like the content you find here, and want to support more content like it,
 
 If you'd like to contribute financially towards the effort (or any of my other OSS work) aside from purchasing the books, I do have a [patreon](https://www.patreon.com/getify) that I would always appreciate your generosity towards.
 
-<a href="https://www.patreon.com/getify">[![patreon.png](https://s11.postimg.org/axpzguh77/patreon.png)](https://www.patreon.com/getify)</a>
+<a href="https://www.patreon.com/getify">[![patreon.png](https://s13.postimg.org/6zi31v493/become_a_patron_button_2x.png)](https://www.patreon.com/getify)</a>
 
 ## In-person Training