Never pass "searchTerm" for "filter" source content type request (#371)

There was an issue when switching from the "search" back to the "filter" source content type.
The "filter" request returned the data from the search request and thus, showed invalid data until the correct data was loaded instead of showing the loading placeholder

Author: schroda

src/screens/SourceMangas.tsx

@@ -121,7 +121,7 @@ const useSourceManga = (
         case SourceContentType.FILTER:
             result = requestManager.useSourceQuickSearch(
                 sourceId,
-                searchTerm ?? '',
+                '',
                 filters.map((filter) => {
                     const { position, state, group } = filter;