test_openapi: Fix a type: ignore issue.
test_openapi: Fix a type: ignore issue.

Signed-off-by: Anders Kaseorg <dfdb7392591db597bc41cf266a9c3bc12a2706e5@zulip.com>

synicalsyntax/zulip,brainwane/zulip,punchagan/zulip,hackerkid/zulip,kou/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip,rht/zulip,brainwane/zulip,rht/zulip,punchagan/zulip,hackerkid/zulip,showell/zulip,zulip/zulip,andersk/zulip,showell/zulip,eeshangarg/zulip,brainwane/zulip,synicalsyntax/zulip,zulip/zulip,kou/zulip,andersk/zulip,synicalsyntax/zulip,hackerkid/zulip,zulip/zulip,rht/zulip,showell/zulip,rht/zulip,kou/zulip,eeshangarg/zulip,synicalsyntax/zulip,rht/zulip,showell/zulip,hackerkid/zulip,punchagan/zulip,brainwane/zulip,andersk/zulip,synicalsyntax/zulip,andersk/zulip,hackerkid/zulip,showell/zulip,andersk/zulip,kou/zulip,showell/zulip,zulip/zulip,eeshangarg/zulip,kou/zulip,brainwane/zulip,kou/zulip,synicalsyntax/zulip,kou/zulip,eeshangarg/zulip,zulip/zulip,punchagan/zulip,eeshangarg/zulip,rht/zulip,punchagan/zulip,eeshangarg/zulip,brainwane/zulip,showell/zulip,eeshangarg/zulip,brainwane/zulip,synicalsyntax/zulip,zulip/zulip,zulip/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip