Dedupe modifier-comment-possible line numbers of method defintion comment

Author: tompng

lib/rdoc/parser/prism_ruby.rb

@@ -521,7 +521,7 @@ def add_method(method_name, receiver_name:, receiver_fallback_type:, visibility:
       receiver,
       comment: comment,
       directives: directives,
-      modifier_comment_lines: [start_line, args_end_line, end_line],
+      modifier_comment_lines: [start_line, args_end_line, end_line].uniq,
       line_no: start_line,
       visibility: visibility,
       singleton: singleton,