update CHANGELOG.rst for 1.0.3
update CHANGELOG.rst for 1.0.3

AtonLerin/pymel,david-lassonde-adsk/pymel,shrtcww/pymel,juggernate/pymel,juggernate/pymel,assumptionsoup/pymel,shrtcww/pymel,leonsooi/pymel,assumptionsoup/pymel,AtonLerin/pymel,leonsooi/pymel,david-lassonde-adsk/pymel