Use imperative mood in constructor docstring.

Resolves D401 in pydocstyle and flake8.

Signed-off-by: Steven! Ragnarök <steven@nuclearsandwich.com>

tracetools_launch/tracetools_launch/action.py

@@ -54,7 +54,7 @@ class Trace(Action):
         **kwargs,
     ) -> None:
         """
-        Constructor.
+        Create a Trace.
 
         :param session_name: the name of the tracing session
         :param append_timestamp: whether to append timestamp to the session name