Fix tests (#497)

* pytest-asyncio 0.15.0 is broken

* require immutabledict>=1.3.0

Author: escapewindow

requirements.txt

@@ -4,7 +4,7 @@ arrow>=1.0
 cryptography>=2.6.1
 dictdiffer
 github3.py
-immutabledict
+immutabledict>=1.3.0
 jsonschema
 json-e>=2.5.0
 PyYAML

tox.ini

@@ -27,7 +27,8 @@ deps =
     flake8_docstrings
     mock
     pytest
-    pytest-asyncio
+    # https://github.com/pytest-dev/pytest-asyncio/issues/209
+    pytest-asyncio!=0.15.0
     pytest-cov
     pytest-mock
     pytest-random-order