types: improve relation types (#9016)

src/steps/Steps.tsx

@@ -1,11 +1,9 @@
-import { PropType, defineComponent, ExtractPropTypes } from 'vue';
+import { PropType, defineComponent, ExtractPropTypes, InjectionKey } from 'vue';
 import { createNamespace } from '../utils';
 import { useChildren } from '@vant/use';
 
 const [name, bem] = createNamespace('steps');
 
-export const STEPS_KEY = Symbol(name);
-
 export type StepsDirection = 'horizontal' | 'vertical';
 
 const props = {
@@ -33,6 +31,8 @@ export type StepsProvide = {
   onClickStep: (index: number) => void;
 };
 
+export const STEPS_KEY: InjectionKey<StepsProvide> = Symbol(name);
+
 export default defineComponent({
   name,