Update libpso link

Updated the link of the libpso repo from github to sharnoth

README.md

@@ -5,7 +5,7 @@
 * `cargo test` to run tests
 
 # development setup
-grab [libpso](https://github.com/jakeprobst/libpso) and put
+grab [libpso](http://git.sharnoth.com/jake/libpso) and put
 ```
 [patch."http://git.sharnoth.com/jake/libpso"]  
 libpso = { path = "path/to/libpso" }