Update Mysql2::Result spec for Ruby 3.1
Update Mysql2::Result spec for Ruby 3.1

Ruby 3.1 immediately raise a TypeError if you try to
instantiate a class that doesn't have an allocator,
which is what we want anyways.

sodabrew/mysql2,jeremy/mysql2,brianmario/mysql2,brianmario/mysql2,sodabrew/mysql2,brianmario/mysql2,jeremy/mysql2,jeremy/mysql2,sodabrew/mysql2