fix: Export missing type AnimationConfig (#2128)

Author: dubzzz

.changeset/cool-brooms-boil.md

@@ -0,0 +1,5 @@
+---
+'@react-spring/core': patch
+---
+
+Export missing type AnimationConfig

packages/core/src/types/objects.ts

@@ -4,6 +4,8 @@ import type { AnimationConfig } from '../AnimationConfig'
 import type { SpringValue } from '../SpringValue'
 import type { Readable } from './internal'
 
+export type { AnimationConfig }
+
 /** The object type of the `config` prop. */
 export type SpringConfig = Partial<AnimationConfig>