Sanitize includes in random_number_generator.cpp

I have no idea how those got there, but now its dependency graph
is much saner.

src/catch2/internal/catch_random_number_generator.cpp

@@ -6,9 +6,6 @@
  */
 
 #include <catch2/internal/catch_random_number_generator.hpp>
-#include <catch2/internal/catch_context.hpp>
-#include <catch2/internal/catch_run_context.hpp>
-#include <catch2/interfaces/catch_interfaces_config.hpp>
 
 namespace Catch {