Remove suspicious group inside type parameter character class

This group was added in 06c314b. I'm not sure
what the intent was here. Oniguruma parses (?:+) as regular characters. [,] is
parsed as a nested character class and so is equivalent to just a bare comma.
So the addition of this group to the character class really just means that
parentheses and colons are now part of the (negated) class. I don't believe
this was the intent, so I've removed the group entirely.

Syntaxes/Vala.tmLanguage

@@ -863,7 +863,7 @@
 					<key>begin</key>
 					<string>\b((?:[a-z]\w*\.)*[A-Z]+\w*)&lt;</string>
 					<key>end</key>
-					<string>&gt;|[^\w\s,\?&lt;\[(?:[,]+)\]]</string>
+					<string>&gt;|[^\w\s,\?&lt;\[\]]</string>
 					<key>name</key>
 					<string>storage.type.generic.vala</string>
 					<key>patterns</key>