Remove Rails deprecation warning in CommitStatus

This removes the deprecation warning:

```
DEPRECATION WARNING: Class level methods will no longer inherit
scoping from `match_id_and_lock_version` in Rails 6.1. To continue using
the scoped relation, pass it into the block directly. To instead access
the full set of models, as Rails 6.1 will, use `CommitStatus.unscoped`,
or `CommitStatus.default_scoped` if a model has default scopes. (called
from block (2 levels) in <class:CommitStatus> at
/home/git/app/models/commit_status.rb:69
```

This was introduced in https://github.com/rails/rails/pull/35186.

app/models/commit_status.rb

@@ -66,7 +66,7 @@ class CommitStatus < ApplicationRecord
     # it expects that items are an array of attributes to match
     # each hash needs to have `id` and `lock_version`
     slice.inject(self) do |relation, item|
-      match = CommitStatus.where(item.slice(:id, :lock_version))
+      match = CommitStatus.unscoped.where(item.slice(:id, :lock_version))
       relation.or(match)
     end
   end