Bump dev deps versions

pyproject.toml

@@ -14,18 +14,18 @@ section-index = "mkdocs_section_index.plugin:SectionIndexPlugin"
 [tool.poetry.dependencies]
 python = "^3.6"
 mkdocs = "^1.1"
-dataclasses = {version = ">=0.7", python = "<3.7"}
+dataclasses = {version = ">=0.7, <1.0", python = "<3.7"}
 
 [tool.poetry.dev-dependencies]
 pytest = "^6.1.2"
-pytest-golden = "^0.1.0"
+pytest-golden = ">=0.2.0"
 testfixtures = "^6.15.0"
-MechanicalSoup = "^0.12.0"
-black = "^20.8b1"
+MechanicalSoup = ">=0.12.0, <1.0"
+black = ">=20.8b1"
 isort = "^5.6.4"
 autoflake = "^1.4"
-pytype = {version = "^2021.04.15", markers = "python_version>='3.6' and python_version<'3.10' and sys_platform!='win32'"}  # Skip on Windows
-mkdocs-material = "^6.1.5"
+pytype = {version = ">=2021.04.15", markers = "python_version>='3.6' and python_version<'3.10' and sys_platform!='win32'"}  # Skip on Windows
+mkdocs-material = ">=6.1.5, <9.0"
 
 [tool.black]
 line-length = 100