ENUM_NAME_OVERRIDES not applying if choice values include a blank string as an option.

[trumpet2012]

Describe the bug
ENUM_NAME_OVERRIDES is not using the custom name specified for the enum if the choice values include a blank string as an option.

This looks to be due to a difference in how the hashes are being computed for the choices in https://github.com/tfranzel/drf-spectacular/blob/master/drf_spectacular/plumbing.py#L778 and https://github.com/tfranzel/drf-spectacular/blob/master/drf_spectacular/hooks.py#L62.

When storing the overriden choice hash the null and blank values are included in the hashing, while when the choices are processed in the enum hook the null and blank values get excluded. This leads to the hash values not matching and the override not being detected.

To Reproduce
Create a choices objects that contains a blank string as a valid value.

// choices.py
class Answers(models.TextChoices):
    YES = "yes", "Yes"
    NO = "no", "No"
    UNSPECIFIED = "", ""

// settings.py
SPECTACULAR_SETTINGS = {
   ...
    "ENUM_NAME_OVERRIDES": {
        'YesNoAnswerEnum': "path.to.choices.Answers"
    }
}

Expected behavior
The name of the Answers choices in the schema should be YesNoAnswerEnum after applying the override.