Fix tests broken by pytest-asyncio breaking-changes#754

habara-k merged 1 commit intomasterline/line-bot-sdk-python:masterfrom

users/habara-keigo/NO-ISSUE-fix-tests-pytest-asyncioline/line-bot-sdk-python:users/habara-keigo/NO-ISSUE-fix-tests-pytest-asyncioCopy head branch name to clipboard