fix dupe param

mastodon_email_bridge/mastodon_email_bridge.py

@@ -438,7 +438,7 @@ class MastodonEmailBridge:
 )
 @click.option(
     '--subjet-template',
-    '-t',
+    '-U',
     default='{{ data["account"]["display_name"] }} ({{ data["account"]["username"] }}) {% if data["in_reply_to_id"] %}replied {% else %}posted{% endif %}{% for tag in data["tags"] %} #{{ tag["name"] }}{% endfor %}',
     help='Jinja2 template for the subject of the emails.'
 )