Added verified version

Author: rotarymars

reference/unordered_set/unordered_set/contains.md

@@ -70,7 +70,7 @@ contain
 - C++20
 
 ### 処理系
-- [Clang](/implementation.md#clang):
+- [Clang](/implementation.md#clang): 14.0.6 [mark verified]
 - [GCC](/implementation.md#gcc): 9.1 [mark verified]
 - [Visual C++](/implementation.md#visual_cpp): 2019 Update 1 [mark verified]