AnimatedRotateComponent [nfc]: Add simple type annotation.

With the new Flow version (0.122.0) coming along with the React
Native v0.63 upgrade (zulip#4245), this would be flagged with a "Could
not decide which case to select" error.

I'm not sure why it has trouble distinguishing this array of strings
from a possible array of numbers, but it's simple enough to just
annotate it as an array of strings, so, might as well.

src/animation/AnimatedRotateComponent.js

@@ -27,7 +27,7 @@ export default class AnimatedRotateComponent extends PureComponent<Props> {
     const { children, style } = this.props;
     const rotation = this.rotation.interpolate({
       inputRange: [0, 360],
-      outputRange: ['0deg', '360deg'],
+      outputRange: (['0deg', '360deg']: string[]),
     });
     const animatedStyle = { transform: [{ rotate: rotation }] };