Properly tokenize fence closing in GitHub style code blocks

src/markdown/markdown.ts

@@ -135,7 +135,7 @@ export const language = <languages.IMonarchLanguage>{
 
 		// github style code blocks
 		codeblockgh: [
-			[/```\s*$/, { token: 'variable.source', next: '@pop', nextEmbedded: '@pop' }],
+			[/```\s*$/, { token: 'string', next: '@pop', nextEmbedded: '@pop' }],
 			[/[^`]+/, 'variable.source']
 		],