default_value for an enum type doesn't work when the enum type is defined with the shorthand syntax

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If submitting a bug, please provide the following:

Environment

• Elixir version (elixir -v):

Erlang/OTP 23 [erts-11.2] [source] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [hipe]

Elixir 1.11.4 (compiled with Erlang/OTP 23)

• Absinthe version (mix deps | grep absinthe): 1.6.3
• Client Framework and version (Relay, Apollo, etc): Not relevant as it's a backend bug

Expected behavior

Define an enum type with the shorthand syntax:

enum :example_type, values: [:A, :B, :C]

In the schema, have a field with default value: arg :example, :example_type, default_value: :A.

It should work as expected.

Actual behavior

A compilation error is thrown:

(ArgumentError) you attempted to apply :value on [:A, :B, :C]. If you are using apply/3, make sure the module is an atom. If you are using the dot syntax, such as map.field or module.function(), make sure the left side of the dot is an atom or a map
    :erlang.apply([:A, :B, :C], :value, [])
Stacktrace:
  │ (absinthe 1.6.3) lib/absinthe/phase/schema/validation/default_enum_value_present.ex:33: anonymous fn/1 in Absinthe.Phase.Schema.Validation.DefaultEnumValuePresent.validate_defaults/2
  │ (elixir 1.11.4) lib/enum.ex:1411: Enum."-map/2-lists^map/1-0-"/2
  │ (absinthe 1.6.3) lib/absinthe/phase/schema/validation/default_enum_value_present.ex:33: Absinthe.Phase.Schema.Validation.DefaultEnumValuePresent.validate_defaults/2
  │ (absinthe 1.6.3) lib/absinthe/blueprint/transform.ex:16: anonymous fn/3 in Absinthe.Blueprint.Transform.prewalk/2
  │ (absinthe 1.6.3) lib/absinthe/blueprint/transform.ex:109: Absinthe.Blueprint.Transform.walk/4
  │ (elixir 1.11.4) lib/enum.ex:1533: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
  │ (absinthe 1.6.3) lib/absinthe/blueprint/transform.ex:145: anonymous

I had to change the definition of the enum type like this:

  enum :example_type do
    value :A
    value :B
    value :C
  end

for it to work, even though it seems that they should mean the exact same thing.