feat(pkg): use dependency group for docs deps

Signed-off-by: Braden Mars <bradenmars@bradenmars.me>

pyproject.toml

@@ -32,7 +32,7 @@ psutil = "~5.8"
 Wand = "~0.6"
 rich = "~9.10"
 
-[tool.poetry.dev-dependencies]
+[tool.poetry.group.dev.dependencies]
 autoflake = "^1.4"
 coveralls = "^3.0.0"
 flake8 = "^3.8.4"
@@ -46,18 +46,18 @@ mypy = "^0.800"
 pytest-sugar = "^0.9.4"
 pytest-cov = "^2.11.1"
 bump2version = "^1.0.1"
-# docs extras
-sphinx = { version = "^3.4.3", optional = true }
-sphinx-autodoc-typehints = { version = "^1.11.1", optional = true }
-recommonmark = { version = "^0.7.1", optional = true }
-sphinx_rtd_theme = {version = "^0.5.1", optional = true}
 
-[tool.poetry.extras]
-docs = ["sphinx", "sphinx-autodoc-typehints", "recommonmark", "sphinx_rtd_theme"]
 
-[tool.dephell.main]
-from = { format = "poetry", path = "pyproject.toml" }
-to = { format = "setuppy", path = "setup.py" }
+[tool.poetry.group.docs]
+optional = true
+
+
+[tool.poetry.group.docs.dependencies]
+sphinx = "^3.4.3"
+sphinx-autodoc-typehints = "^1.11.1"
+recommonmark = "^0.7.1"
+sphinx_rtd_theme = "^0.5.1"
+
 
 [tool.black]
 line-length = 100
@@ -105,5 +105,5 @@ exclude_lines = """
 	"""
 
 [build-system]
-requires = ["poetry-core>=1.0.0"]
+requires = ["poetry-core"]
 build-backend = "poetry.core.masonry.api"