Fixing --subpath on newer gradio version

[catalpaaa]

Description

--subpath got broken again after gradio 3.30, updated it to work with 3.30+

Screenshots/videos:

before:

after:

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests

[catalpaaa]

tested with nginx config using --listen --port 9438 --subpath stable-diffusion

location /stable-diffusion/ {
	proxy_http_version 1.1;
	proxy_set_header Accept-Encoding gzip;
	proxy_set_header Upgrade $http_upgrade;
	proxy_set_header Connection "upgrade";
	proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
	proxy_set_header   X-Real-IP		$remote_addr;
	proxy_pass	http://localhost:9438/;
}

[AUTOMATIC1111]

would it break if no subpath is specified?

[AUTOMATIC1111]

the answer is yes

[catalpaaa]

the answer is yes

aww, forgot about that part