[build] Post-release bump to 0.5.3
[build] Post-release bump to 0.5.3

pwithnall/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,clutter-project/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx