[animations] Bump minimum Flutter version (#5596)

Bumps minimum Fluter version to fix #4898 (comment).

Author: camsim99

packages/animations/pubspec.yaml

@@ -6,7 +6,7 @@ version: 2.0.9
 
 environment:
   sdk: ">=3.1.0 <4.0.0"
-  flutter: ">=3.13.0"
+  flutter: ">=3.16.0"
 
 dependencies:
   flutter: