Add missing include for VxWorks build.

std::min is defined in algorithm provides std::min. It appears to be transitively included for most platforms. For VxWorks however this explicit include is required.

src/catch2/internal/catch_sharding.hpp

@@ -11,6 +11,7 @@
 #include <catch2/catch_session.hpp>
 
 #include <cmath>
+#include <algorithm>
 
 namespace Catch {