Fix warnings with VS2019 in C++20 mode (#4173)

imgui_internal.h

@@ -63,7 +63,9 @@ Index of this file:
 #pragma warning (disable: 4251)     // class 'xxx' needs to have dll-interface to be used by clients of struct 'xxx' // when IMGUI_API is set to__declspec(dllexport)
 #pragma warning (disable: 26812)    // The enum type 'xxx' is unscoped. Prefer 'enum class' over 'enum' (Enum.3). [MSVC Static Analyzer)
 #pragma warning (disable: 26495)    // [Static Analyzer] Variable 'XXX' is uninitialized. Always initialize a member variable (type.6).
-
+#if defined(_MSC_VER) && _MSC_VER >= 1922 // MSVC 2019 16.2 or later
+#pragma warning (disable: 5054)     // operator '|': deprecated between enumerations of different types
+#endif
 #endif
 
 // Clang/GCC warnings with -Weverything