Downcase keys in result row hash.

[vanne]

For me MySQL (Percona server 8.0.13) is returning all caps keys
in the result row hash:

[1] pry(#<ActiveRecord::ConnectionAdapters::Mysql2Adapter>)> row
=> {"VIEW_DEFINITION"=>
  "select .......

The result is that db:schema:dump is failing:

rails aborted!
NoMethodError: undefined method `gsub!' for nil:NilClass
/........./vendor/bundle/ruby/2.4.0/bundler/gems/schema_plus_views-71dce2030147/lib/schema_plus/views/active_record/connection_adapters/mysql2_adapter.rb:12:in `block in view_definition'