fix: typing

src/csv-loader/loader.ts

@@ -18,7 +18,7 @@ interface PropertyConfig {
 export default function csvLoader(
   this: LoaderContext<CsvLoaderOptions>,
   content: string
-): string {
+): string | Buffer {
   const options = this.getOptions() || {};
   const delimiter = options.delimiter ?? ',';
   const quote = options.quote ?? '"';