Change an assertion to get test passing both with MySQL 5 and 8

MDL-75856 has been created about to normalize that bit, but
I need to get local_ci passing in order to change other stuff,
hence accepting both 18 and 19 as valid outcome.

Author: stronk7

tests/1-compare_databases.bats

@@ -107,9 +107,9 @@ setup () {
     assert_output --partial 'Column status of table enrol_lti_app_registration difference found in has_default: true !== false'
     assert_output --partial 'Column status of table enrol_lti_app_registration difference found in default_value: 0 !== null'
     assert_output --partial 'Column hidden of table grade_categories difference found in type: tinyint !== bigint'
-    assert_output --partial 'Column hidden of table grade_categories difference found in max_length: 2 !== 18'
+    assert_output --regexp 'Column hidden of table grade_categories difference found in max_length: 2 !== 1[89]'
     assert_output --partial 'Column hidden of table grade_categories_history difference found in type: tinyint !== bigint'
-    assert_output --partial 'Column hidden of table grade_categories_history difference found in max_length: 2 !== 18'
+    assert_output --regexp 'Column hidden of table grade_categories_history difference found in max_length: 2 !== 1[89]'
     assert_output --partial 'Error: Problem comparing databases ci_installed_'
     assert_output --partial 'Error: Process ended with 1 errors'
     refute_output --partial 'Ok: Process ended without errors'