Added compiler flag to ignore warnings related to narrowing conversions

I know it's bad practice, but I didn't see any other alternative, as this seemed to be an
issue with raygui.

meson.build

@@ -1,5 +1,5 @@
 project('Pong', ['cpp', 'c'], version: '0.1')
-add_global_arguments('-g', '-Wall', '-pedantic', '-Wno-unused-function', language : ['cpp', 'c'])
+add_global_arguments('-g', '-Wall', '-pedantic', '-Wno-unused-function', '-Wno-narrowing', language : ['cpp', 'c'])
 compiler = meson.get_compiler('cpp')
 cmake = import('cmake')