chore(WorkspaceBuilder): Improve code around new session args

Author: tony

tmuxp/workspacebuilder.py

@@ -205,15 +205,14 @@ def build(self, session=None, append=False):
                     "Session name %s is already running." % self.sconf["session_name"]
                 )
             else:
+                new_session_kwargs = {}
                 if "start_directory" in self.sconf:
-                    session = self.server.new_session(
-                        session_name=self.sconf["session_name"],
-                        start_directory=self.sconf["start_directory"],
-                    )
-                else:
-                    session = self.server.new_session(
-                        session_name=self.sconf["session_name"]
-                    )
+                    new_session_kwargs["start_directory"] = self.sconf[
+                        "start_directory"
+                    ]
+                session = self.server.new_session(
+                    session_name=self.sconf["session_name"]
+                )
 
             assert self.sconf["session_name"] == session.name
             assert len(self.sconf["session_name"]) > 0