fix: comment typo (#12898)

superset/config.py

@@ -854,7 +854,7 @@ class CeleryConfig:  # pylint: disable=too-few-public-methods
 # The id of a template dashboard that should be copied to every new user
 DASHBOARD_TEMPLATE_ID = None
 
-# A callable that allows altering the database conneciton URL and params
+# A callable that allows altering the database connection URL and params
 # on the fly, at runtime. This allows for things like impersonation or
 # arbitrary logic. For instance you can wire different users to
 # use different connection parameters, or pass their email address as the