Lock idna pip package for certbot

plugins/_module/pip_update.py

@@ -20,6 +20,7 @@ def main():
         'docutils': '0.15.2',# botocore requires <16
         'msgpack': '0.5.6',# Required for BorgBackup
         'chardet': '3.0.4',# Certbot fails with 4.0.0
+        'idna': '2.10',# Certbot fails with 3.0
     }
     mode = module.params['mode']
     executable = module.params['executable']