fix(TS): improve typescript types for MDX component

Author: kentcdodds

src/client.ts

@@ -1,14 +1,18 @@
 import * as React from 'react'
 
+interface ComponentMap {
+  [name: string]: React.ComponentType | string | ComponentMap
+}
+
+interface MDXContentProps {
+  [props: string]: unknown
+  components?: ComponentMap
+}
+
 function getMDXComponent(
   code: string,
   globals?: Record<string, unknown>,
-): React.FunctionComponent<{
-  components?: Record<
-    string,
-    React.FunctionComponent | React.Component | string
-  >
-}> {
+): React.FunctionComponent<MDXContentProps> {
   const scope = {React, ...globals}
   // eslint-disable-next-line
   const fn = new Function(...Object.keys(scope), code)