[ImgBot] optimizes images

*Total -- 8.61kb -> 6.08kb (29.38%)

/android/app/src/main/res/drawable-xxxhdpi/ic_stat_onesignal_default.png -- 3.29kb -> 2.06kb (37.34%)
/android/app/src/main/res/drawable-xxhdpi/ic_stat_onesignal_default.png -- 2.17kb -> 1.42kb (34.83%)
/android/app/src/main/res/drawable-xhdpi/ic_stat_onesignal_default.png -- 1.46kb -> 1.10kb (24.93%)
/android/app/src/main/res/drawable-hdpi/ic_stat_onesignal_default.png -- 0.98kb -> 0.84kb (14.81%)
/android/app/src/main/res/drawable-mdpi/ic_stat_onesignal_default.png -- 0.71kb -> 0.67kb (5.1%)

Author: ImgBotApp