Mark registerNodeForIncrementalParse as mutating

Author: StevenWong12

Sources/SwiftParser/Parser.swift

@@ -678,7 +678,7 @@ extension Parser {
     return nil
   }
 
-  func registerNodeForIncrementalParse(node: RawSyntax, startToken: Lexer.Lexeme) {
+  mutating func registerNodeForIncrementalParse(node: RawSyntax, startToken: Lexer.Lexeme) {
     guard let parseNodeAffectRange else {
       return
     }