remove tomlkit from poetry-core

tomli is smaller, faster, and being adopted by the standard library.

poetry-core has no need of the extra features that tomlkit brings.

Author: dimbleby

poetry.lock

@@ -51,6 +51,7 @@ tox = "^3.0"
 vendoring = {version = "^1.0", python = "^3.8"}
 build = "^0.7.0"
 mypy = ">=0.960"
+tomli-w = "^1.0.0"
 types-jsonschema = ">=4.4.4"
 types-setuptools = ">=57.4.14"
 
@@ -91,7 +92,6 @@ exclude = "(?x)(^tests/.*/fixtures | ^src/poetry/core/_vendor)"
 [[tool.mypy.overrides]]
 module = [
   'lark.*',
-  'tomlkit.*',
   'virtualenv.*',
 ]
 ignore_missing_imports = true