adding clang/gcc suppression of the deprecation warnings.

tests/multi_span_tests.cpp

@@ -18,9 +18,13 @@
 // blanket turn off warnings from CppCoreCheck from catch
 // so people aren't annoyed by them when running the tool.
 #pragma warning(disable : 26440 26426) // from catch 
-#pragma warning(disable : 4996) // multi_span is in the process of being deprecated. 
+//#pragma warning(disable : 4996) // multi_span is in the process of being deprecated. 
                                 // Suppressing warnings until it is completely removed
+#endif
 
+#if __clang__ || __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 #endif
 
 #include <catch/catch.hpp> // for AssertionHandler, StringRef, CHECK, CHECK...
@@ -1785,3 +1789,7 @@ TEST_CASE("iterator")
 #ifdef CONFIRM_COMPILATION_ERRORS
 copy(src_span_static, dst_span_static);
 #endif
+
+#if __clang__ || __GNUC__
+#pragma GCC diagnostic pop
+#endif