Update TS type file to include jsonpatch formatter (#310)

Co-authored-by: Thilina Herath <[email protected]>

Author: thilinatnt

src/index.d.ts

@@ -190,6 +190,7 @@ export const formatters: {
   annotated: Formatter;
   console: Formatter;
   html: HtmlFormatter;
+  jsonpatch: Formatter;
 };
 
 export const console: Formatter;