How to set proxy while using googletrans lib python

UPDATE: Based on the error described in the comments, you show use the following code. Tested on my environment point to a proxy on cloud:

Whitout password:

from googletrans import Translator
from httpcore import SyncHTTPProxy

proxy={"https": SyncHTTPProxy((b'http', b'<proxy server ip>', 3128, b''))}

# http = proxy protocol
# <proxy server ip> = proxy server ip / localhost if its local
# 3128 = proxy server port, change to yours


translator = Translator(service_urls=['translate.googleapis.com'],proxies=proxy)
translation = translator.translate("Der Himmel ist blau und ich mag Bananen", dest='en')
print(translation.text)

With Password authentication:

from googletrans import Translator
from httpcore import SyncHTTPProxy
from base64 import b64encode


def build_proxy_headers(username, password):
    userpass = (username.encode("utf-8"), password.encode("utf-8"))
    token = b64encode(b":".join(userpass))
    return [(b"Proxy-Authorization", b"Basic " + token)]


proxy_url=(b"http", b"<my_proxy_host_ip> ", 3128, b'')     # <my_proxy_host_ip> as `bytes`, <my_proxy_port> as `int`
proxy_headers = build_proxy_headers("<username>","<password>" )  # <my_username>, <my_password> as `str`
proxy={"https": SyncHTTPProxy(proxy_url=proxy_url, proxy_headers=proxy_headers) }

translator = Translator(service_urls=['translate.googleapis.com'],proxies=proxy)
translation = translator.translate("Der Himmel ist blau und ich mag Bananen", dest='en')
print(translation.text)

Previous answer

The googletrans uses the httpx library, you can follow its documentation do configure the proxy connection:

send the proxy data in a dictionary variable:

proxies_def = {
    "http://": "http://localhost:8030",
    "https://": "http://localhost:8031",
}

#Or with authentication:
proxies_def = {
    "http://": "http://username:password@localhost:8030",
    # ...
}

from googletrans import Translator
translator = Translator(proxies=proxies_def)

Check the httpx documentation here.