fix: uni-loading 内部函数this指向问题

uni_modules/uni-loading/components/uni-loading/circle.uvue

@@ -60,7 +60,7 @@
 					const easedProgress = easeInOutCubic(progress);
 					return easedProgress
 				}
-				function draw() {
+				const draw = () => {
 
 					ctx.reset();
 					ctx.beginPath();