The previous commit removed the only user of QAPIGen(None).  Tighten
the type hint.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 scripts/qapi/gen.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
index cb00229f5d..8716689450 100644
--- a/scripts/qapi/gen.py
+++ b/scripts/qapi/gen.py
@@ -37,7 +37,7 @@ from .source import QAPISourceInfo
 
 
 class QAPIGen:
-    def __init__(self, fname: Optional[str]):
+    def __init__(self, fname: str):
         self.fname = fname
         self._preamble = ''
         self._body = ''
-- 
2.26.2