Bump database_cleaner from 1.7.0 to 1.8.1 (#1480)

Bumps [database_cleaner](https://github.com/DatabaseCleaner/database_cleaner) from 1.7.0 to 1.8.1.
- [Release notes](https://github.com/DatabaseCleaner/database_cleaner/releases)
- [Changelog](https://github.com/DatabaseCleaner/database_cleaner/blob/master/History.rdoc)
- [Commits](https://github.com/DatabaseCleaner/database_cleaner/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Gemfile.lock

@@ -129,7 +129,7 @@ GEM
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     crass (1.0.6)
-    database_cleaner (1.7.0)
+    database_cleaner (1.8.1)
     debug_inspector (0.0.3)
     devise (4.7.1)
       bcrypt (~> 3.0)