__post_init__ not called from replace

[kramar11]

Description

When using msgspec.structs.replace to create a new object, the __post_init__ method is not called (unlike with dataclass.replace).

from dataclasses import dataclass, replace
import msgspec
                                                                                                                   
@dataclass
class D:                                                                                                           
    x: int
    def __post_init__(self):
        print("dataclass: post init called")
                                                                                                                   
                                                                                                                   
class M(msgspec.Struct):                                                                                           
    x: int                                                                                                         
    def __post_init__(self):                                                                                       
        print("msgspec: post init called")                                                                         
                                                                                                                   
                                                                                                                   
d = D(1)                                                                                                           
m = M(1)                                                                                                           
                                                                                                                   
d2 = replace(d, x=2)                                                                                               
m2 = msgspec.structs.replace(m, x=2) 

# Output:
# dataclass: post init called
# msgspec: post init called
# dataclass: post init called

Tested with python 3.13.5.