Allow support for Python 3.8 and 3.9

poetry.lock

@@ -637,7 +637,7 @@ testing = ["pytest (>=4.6)", "pytest-checkdocs (>=1.2.3)", "pytest-flake8", "pyt
 [metadata]
 content-hash = "d7061a714fbdc1ec52f765b2818605719206466c4bc867ba31fc805250b4a97e"
 lock-version = "1.0"
-python-versions = "^3.9"
+python-versions = "^3.8"
 
 [metadata.files]
 appdirs = [

pyproject.toml

@@ -9,7 +9,7 @@ packages = [
 ]
 
 [tool.poetry.dependencies]
-python = "^3.9"
+python = "^3.8"
 requests = "^2.25.1"
 attrs = "^21.2.0"
 cattrs = "^1.7.1"

tox.ini

@@ -1,6 +1,7 @@
 # For more information about tox, see https://tox.readthedocs.io/en/latest/
 [tox]
-envlist = py37,py38,py39,flake8
+envlist = py38,py39,flake8
+isolated_build = True
 
 [testenv]
 ;changedir=tests