docs(readme): remove double "using" (#1295)

README.md

@@ -127,7 +127,7 @@ For more of the story of GoodJob, read the [introductory blog post](https://isla
     - Because of Rails deferred autoloading, jobs enqueued via the `rails console` may not begin executing on a separate server process until the Rails application is fully initialized by loading a web page once.
     - Remember, only Active Job's `perform_later` sends jobs to the queue adapter; Active Job's `perform_now` executes the job immediately and does not invoke the queue adapter. GoodJob is not involved in `perform_now` jobs.
 1. **In Rails' test environment**, by default, GoodJob's Adapter executes jobs `inline` immediately in the current thread.
-    - Future-scheduled jobs can be executed with `GoodJob.perform_inline` using using a tool like Timecop or `ActiveSupport::Testing::TimeHelpers`.
+    - Future-scheduled jobs can be executed with `GoodJob.perform_inline` using a tool like Timecop or `ActiveSupport::Testing::TimeHelpers`.
     - Note that Active Job's TestAdapter, which powers test helpers (e.g. `assert_enqueued_with`), may override GoodJob's Adapter in [some configurations](https://github.com/rails/rails/issues/37270).
 1. **In Rails' production environment**, by default, GoodJob's Adapter enqueues jobs in `external` mode to be executed by a separate execution process:
     - By default, GoodJob separates job enqueuing from job execution so that jobs can be scaled independently of the web server.  Use the GoodJob command-line tool to execute jobs: