Remove the deprecated tool.poetry.dev-dependencies section (#395)

Immediately below the deprecated section is the correct section,
`tool.poetry.group.dev.dependencies`, with the same dependencies list.

`poetry lock` was run to ensure the lock file is in sync.

Author: kurtmckee

poetry.lock

@@ -34,10 +34,6 @@ packages = [
 [tool.poetry.dependencies]
 python = ">=3.7"
 
-[tool.poetry.dev-dependencies]
-pandocfilters = "^1.5"
-setuptools = "68"
-
 [tool.poetry.group.dev.dependencies]
 pandocfilters = "^1.5"
 setuptools = "68"