Fix sub-command option propagation for export

When a lock file does not exist when handling export command, option 
propagation for lock sub-command was incorrect. This change corrects 
this issue.

Resolves: #3309

poetry/console/commands/export.py

@@ -44,11 +44,11 @@ def handle(self):
             self.line("<comment>The lock file does not exist. Locking.</comment>")
             options = []
             if self.io.is_debug():
-                options.append(("-vvv", None))
+                options.append("-vvv")
             elif self.io.is_very_verbose():
-                options.append(("-vv", None))
+                options.append("-vv")
             elif self.io.is_verbose():
-                options.append(("-v", None))
+                options.append("-v")
 
             self.call("lock", options)