JRUBY-3608: Add missing change_column_null method for postgres
JRUBY-3608: Add missing change_column_null method for postgres

keeguon/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,atambo/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,atambo/activerecord-jdbc-adapter,atambo/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter,keeguon/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter,keeguon/activerecord-jdbc-adapter