Merge pull request rails#12311 from kennyj/fix_typo_about_uuid

Fix typo. This test isn't executed even in the postgresql.

Author: rafaelfranca

activerecord/test/cases/schema_dumper_test.rb

@@ -299,7 +299,7 @@ def test_schema_dump_includes_macaddr_shorthand_definition
 
     def test_schema_dump_includes_uuid_shorthand_definition
       output = standard_dump
-      if %r{create_table "poistgresql_uuids"} =~ output
+      if %r{create_table "postgresql_uuids"} =~ output
         assert_match %r{t.uuid "guid"}, output
       end
     end