Fix missing pair for C#

(cherry picked from commit 5aa184e0c0c67f13a8a108a65a4c14126503b473)

src/main/kotlin/com/github/izhangzhihao/rainbow/brackets/visitor/CSharpRainbowVisitor.kt

@@ -55,6 +55,14 @@ class CSharpRainbowVisitor : RainbowHighlightVisitor() {
                 return count
             }
 
+            if (element is LeafPsiElement && type == LPARENTH && element.elementType == RPARENTH) {
+                return count
+            }
+
+            if (element is LeafPsiElement && type == RPARENTH && element.elementType == LPARENTH) {
+                return count
+            }
+
             var nextCount = count
 
             if (element is LeafPsiElement && element.elementType == type) {