Change attribute name
The old one is deprecated as indicated by the current `poetry` version
@@ -37,7 +37,7 @@ astor = "^0.8.0"
[tool.poetry.dev-dependencies]
pytest = "^5.3"
-black = {version = "^19.10b0", allows-prereleases = true}
+black = {version = "^19.10b0", allow-prereleases = true}
flake8 = "^3.7"
pytest-cov = "^2.8"
mypy = "^0.750"
