Unit tests are failing

Affected tests:
tests/test_cloud_event_functions.py:192
tests/test_functions.py:255

```
assert resp.status_code == 400
E       assert 415 == 400
E        +  where 415 = <WrapperTestResponse streamed [415 UNSUPPORTED MEDIA TYPE]>.status_code
```

Repro step:
Run `tox -e py39-macos`