print warnings for 3.3 users (#5283)

fix errors

acme/acme/__init__.py

@@ -10,3 +10,12 @@ supported version: `draft-ietf-acme-01`_.
   https://github.com/ietf-wg-acme/acme/tree/draft-ietf-acme-acme-01
 
 """
+import sys
+import warnings
+
+if sys.version_info[:2] == (3, 3):
+    warnings.warn(
+            "Python 3.3 support will be dropped in the next release of "
+            "acme. Please upgrade your Python version.",
+            PendingDeprecationWarning,
+    ) #pragma: no cover

certbot/main.py

@@ -1215,6 +1215,9 @@ def main(cli_args=sys.argv[1:]):
         # Let plugins_cmd be run as un-privileged user.
         if config.func != plugins_cmd:
             raise
+    if sys.version_info[:2] == (3, 3):
+        logger.warning("Python 3.3 support will be dropped in the next release "
+                    "of Certbot - please upgrade your Python version.")
 
     set_displayer(config)