Update for bucklescript 8

[dfalling]

Updates for BuckleScript 8 changes.

/node_modules/reason-future/src/FutureJs.re 18:5-28:8

  16 │ let fromPromise = (promise, errorTransformer) =>
  17 │   Future.make(callback =>
  18 │     promise
  19 │     |> Js.Promise.then_(res =>
   . │ ...
  27 │          |> Js.Promise.resolve
  28 │        )
  29 │   );
  30 │

  This has type:
    Js.Promise.t(unit) (defined as Js.Promise.t(unit))
  But somewhere wanted:
    unit

bsrefmt made a few other minor changes too automatically. I can back those out if you'd like.

[dfalling]

Fix for the unsafe inferred external name warning.

[coveralls]

Pull Request Test Coverage Report for Build 89

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 98.947%

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Totals
Change from base Build 87:	0.0%
Covered Lines:	161
Relevant Lines:	162

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💛 - Coveralls

[dfalling]

This is the main fix. Without this BuckleScript 8 now doesn't resolve the type as a unit.

[briangorman]

@dfalling Thanks for the PR, once the merge conflict is resolved I will merge.