swagger_serializer_method does not work with partialmethod

[sevdog]

Bug Report

When attempting to use the swagger_serializer_method on a partial object generated with functool.partialmethod the _swagger_serializer is not kept in the final class method.

This prevents from generating a correct swagger file since this approach is used to generate more than 1 fields and thus it is not possible to set the decorator on the original method.

Description

A clear and concise description of the problem...

Minimal Reproduction

from functools import partialmethod
from drf_yasg.utils import swagger_serializer_method
from rest_framework import serializers


class S1(serializers.Serializer):
    f1 = serializers.CharField()


class S2(serializers.Serializer):
    f2 = serializers.SerializeMethodField()

    def _m(self, value, otherser):
        return otherser(value).data

    get_f2 = swagger_serializer_method(S1)(partialmethod(_m, otherser=S1))


class S3(serializers.Serializer):
    f3 = serializers.SerializerMethodField()

    @swagger_serializer_method(S1)
    def get_f3(self, value):
        return S1(value).data

print(S3.get_f3._swagger_serializer)
print(S2.get_f3._swagger_serializer) # AttributeError: 'functools.partial' object has no attribute '_swagger_serializer'

Stack trace / Error message

AttributeError: 'functools.partial' object has no attribute 

Your Environment

Python 3.10.12
djangorestframework==3.14.0
drf-yasg==1.21.7
Django==3.2.22