Report Catch2's version in the xml reporter output

src/catch2/reporters/catch_reporter_xml.cpp

@@ -14,6 +14,7 @@
 #include <catch2/internal/catch_list.hpp>
 #include <catch2/catch_test_case_info.hpp>
 #include <catch2/internal/catch_move_and_forward.hpp>
+#include <catch2/catch_version.hpp>
 
 #if defined(_MSC_VER)
 #pragma warning(push)
@@ -54,7 +55,8 @@ namespace Catch {
             m_xml.writeStylesheetRef( stylesheetRef );
         m_xml.startElement("Catch2TestRun")
              .writeAttribute("name"_sr, m_config->name())
-             .writeAttribute("rng-seed"_sr, m_config->rngSeed());
+             .writeAttribute("rng-seed"_sr, m_config->rngSeed())
+             .writeAttribute("catch2-version"_sr, libraryVersion());
         if (m_config->testSpec().hasFilters())
             m_xml.writeAttribute( "filters"_sr, serializeFilters( m_config->getTestsOrTags() ) );
     }