[utils] Encode hostnames before passing to urllib

With IDN (Internationalized Domain Name) and a proxy, non-ascii URLs
are passed down to urllib/urllib2, causing UnicodeEncodeError

Fixes #8890

youtube_dl/utils.py

@@ -1746,6 +1746,7 @@ def escape_url(url):
     """Escape URL as suggested by RFC 3986"""
     url_parsed = compat_urllib_parse_urlparse(url)
     return url_parsed._replace(
+        netloc=url_parsed.netloc.encode('idna').decode('ascii'),
         path=escape_rfc3986(url_parsed.path),
         params=escape_rfc3986(url_parsed.params),
         query=escape_rfc3986(url_parsed.query),