"auto_spacing" doesn't work

[JingwangLi]

"auto_spacing" doesn't work. Even I also set it as true, there weren't spaces between Chinese and English, just as the following:

My environment information:

hexo: 4.2.0                                                                      
hexo-cli: 3.1.0                                                                  
os: Windows_NT 10.0.18362 win32 x64                                              
node: 12.13.1                                                                    
v8: 7.7.299.13-node.16                                                           
uv: 1.33.1                                                                       
zlib: 1.2.11                                                                     
brotli: 1.0.7                                                                    
ares: 1.15.0                                                                     
modules: 72                                                                      
nghttp2: 1.39.2                                                                  
napi: 5                                                                          
llhttp: 1.1.4                                                                    
http_parser: 2.8.0                                                               
openssl: 1.1.1d                                                                  
cldr: 35.1                                                                       
icu: 64.2                                                                        
tz: 2019c                                                                        
unicode: 12.1