externals: Add catch2 v3.2.1

Merge commit '6879e5bb1c' as 'externals/catch'

externals/catch/tests/SelfTest/TimingTests/Sleep.tests.cpp

@@ -0,0 +1,24 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <chrono>
+#include <thread>
+
+TEST_CASE( "sleep_for_100ms", "[.min_duration_test][approvals]" )
+{
+  std::this_thread::sleep_for( std::chrono::milliseconds( 100 ) );
+  CHECK( true );
+}
+
+TEST_CASE( "sleep_for_1000ms", "[.min_duration_test][approvals]" )
+{
+  std::this_thread::sleep_for( std::chrono::milliseconds( 1'000 ) );
+  CHECK( true );
+}