Explicitly install rack gem (#12972)

Pin rack version to 2.0.8. Rack-2.1.0 and 2.1.1 are known to record error below upon requests to `/sidekiq`:

```
NoMethodError - undefined method `transform_keys' for #<ActionDispatch::Request::Session:0x...>
```
This commit is contained in:
Daigo 3 Dango 2020-01-27 00:06:34 -10:00 committed by Eugen Rochko
parent 663ea84b08
commit 7b8e0d3477
2 changed files with 3 additions and 1 deletions