Check if CrateDB ActiveRecord adapter can be used with `ruby-pg` instead of `crate_ruby`

[amotl]

Hi,

in a similar spirit like crate/crate-dbal#107, it should be investigated if the CrateDB ActiveRecord adapter can be made work with the canonical PostgreSQL driver for Ruby, ruby-pg, instead of using crate_ruby.

See also:

• Clarify purpose of this driver vs. generic PostgreSQL driver crate_ruby#35

With kind regards,
Andreas.