Bump pytest-asyncio from 0.16.0 to 0.21.1

Bumps [pytest-asyncio](https://github.com/pytest-dev/pytest-asyncio) from 0.16.0 to 0.21.1.
- [Release notes](https://github.com/pytest-dev/pytest-asyncio/releases)
- [Commits](pytest-dev/pytest-asyncio@v0.16.0...v0.21.1)

---
updated-dependencies:
- dependency-name: pytest-asyncio
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

setup.py

@@ -3,7 +3,7 @@
 _TEST_REQUIRE = [
     "pytest==6.2.5",
     "pytest-cov==3.0.0",
-    "pytest-asyncio==0.16.0",
+    "pytest-asyncio==0.21.1",
     "pytest-aiohttp==0.3.0",
     "asynctest==0.13.0",
     "pytz",