Fix boot up postgres rails tests, add undefined method `supports_iden…

…tity_columns?'

NoMethodError: undefined method `supports_identity_columns?' for #<ActiveRecord::Schema:0x2cc82c83>
         method_missing at /home/jessec/bryk/vendor_gems/rails/activerecord/lib/active_record/migration.rb:1047
          say_with_time at /home/jessec/bryk/vendor_gems/rails/activerecord/lib/active_record/migration.rb:1017

lib/arjdbc/postgresql/adapter.rb

@@ -232,6 +232,10 @@ def supports_insert_on_conflict?
     alias supports_insert_on_duplicate_update? supports_insert_on_conflict?
     alias supports_insert_conflict_target? supports_insert_on_conflict?
 
+    def supports_identity_columns? # :nodoc:
+      database_version >= 10_00_00 # >= 10.0
+    end
+
     def index_algorithms
       { concurrently: 'CONCURRENTLY' }
     end