build: remove VERSION_MIN_REQUIRED and VERSION_MAX_ALLOWED

When compiling the code, there were no deprecation warnings (except for
g_type_class_adjust_private_offset()).

To have all deprecation warnings, the only solution is to not use
VERSION_MIN_REQUIRED and VERSION_MAX_ALLOWED...

Having the min_required at 2.34 and max_allowed at 2.38 doesn't work.
Having only min_required or only max_allowed doesn't work too.
I think I tried all the possibilities.

The purpose of having the min_required and max_allowed was to make sure
that the required versions were correct. Now if we use a new symbol, we
must update the required version, we won't get warnings about that.