community/py3-requests-gssapi: fix source url
>>> py3-requests-gssapi: Fetching py3-requests-gssapi-1.3.0.tar.gz::https://github.com/pythongssapi/requests-gssapi/releases/download/v1.3.0/requests-gssapi-1.3.0.tar.gz
Connecting to github.com (140.82.121.3:443)
wget: server returned error: HTTP/1.1 404 Not Found