Exclude markup.italic scope from italic fix

This prevents the case of the rule from the main grammar having already being entered and not being able to exit as expected.

Author: infininight

Syntaxes/Markdown (GitHub Italics).tmLanguage

@@ -7,7 +7,7 @@
 	<key>hideFromUser</key>
 	<true/>
 	<key>injectionSelector</key>
-	<string>(L:text.html.markdown)</string>
+	<string>L:(text.html.markdown - (markup.italic.markdown))</string>
 	<key>name</key>
 	<string>Markdown (GitHub Italics)</string>
 	<key>patterns</key>