Reflect the closure of xenia-project#1333

xenia-project#1333 has been closed, so the README should reflect that.
This line can be replaced with another suggestion from the good-first-issue tag.

README.md

@@ -61,7 +61,6 @@ Fixes and optimizations are always welcome (please!), but in addition to
 that there are some major work areas still untouched:
 
 * Help work through [missing functionality/bugs in games](https://github.com/xenia-project/xenia/labels/compat)
-* Add input drivers for [third-party controllers](https://github.com/xenia-project/xenia/issues/1333)
 * Skilled with Linux? A strong contributor is needed to [help with porting](https://github.com/xenia-project/xenia/labels/platform-linux)
 
 See more projects [good for contributors](https://github.com/xenia-project/xenia/labels/good%20first%20issue). It's a good idea to ask on Discord and check the issues page before beginning work on