Bump dev deps versions

Author: oprypin

pyproject.toml

@@ -24,13 +24,13 @@ cached-property = "^1.5.2; python_version<'3.8'"
 Jinja2 = ">=2.11.2, <4.0"
 
 [tool.poetry.dev-dependencies]
-mkdocs-material = ">=6.0.2, <8"
+mkdocs-material = ">=6.0.2, <9.0"
 pytest = "^6.1.2"
-pytest-golden = "^0.2.0"
-black = "^20.8b1"
+pytest-golden = ">=0.2.0"
+black = ">=20.8b1"
 isort = "^5.6.4"
 autoflake = "^1.4"
-pytype = {version = ">=2020.10.8", markers = "python_version>='3.6' and python_version<'3.9' and sys_platform!='win32'"}  # Skip on Windows
+pytype = {version = ">=2021.04.15", markers = "python_version>='3.6' and python_version<'3.9' and sys_platform!='win32'"}  # Skip on Windows
 
 [tool.black]
 line-length = 100