tox.ini: use poetry

tox.ini

@@ -1,13 +1,21 @@
 [tox]
 envlist = py3.9
+isolated_build = true
 
 [testenv]
-deps = -rrequirements.txt
+ignore_errors = true
+deps =
+    pytest==6.2.3
+    pytest-asyncio==0.15.1
+    pytest-cov==2.11.1
+    flake8==3.9.1
+    black==20.8b1
+    mypy==0.812
+    pytest-instafail==0.4.2
 commands =
-    pipenv install --dev
-    pipenv run black --check litecord run.py tests manage
-    pipenv run flake8 litecord run.py tests manage
-    pipenv run pytest {posargs:tests}
+    black --check litecord run.py tests manage
+    flake8 litecord run.py tests manage
+    pytest {posargs:tests}
 
 [flake8]
 max-line-length = 88