fix ignore of mimeTime set in mediaRenderer (#5683)

## Problem solved

CNCT-2634

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## PR-Codex overview
This PR modifies the `isFetched` property in the `useResolvedMediaType.ts` file to include an additional condition for its value, enhancing the logic that determines whether media type data has been successfully fetched.

### Detailed summary
- The `isFetched` property is updated to:
  - Use `resolvedMimeType.isFetched` or check if `mimeType` is truthy (`!!mimeType`).

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Author: dirtycajunrice

packages/thirdweb/src/react/web/ui/MediaRenderer/useResolvedMediaType.ts

@@ -43,6 +43,6 @@ export function useResolvedMediaType(
 
   return {
     mediaInfo: { url: resolvedUrl, mimeType: resolvedMimeType.data },
-    isFetched: resolvedMimeType.isFetched,
+    isFetched: resolvedMimeType.isFetched || !!mimeType,
   };
 }