pyproject.toml: Remove python 3.6 backport packages

Author: tony

pyproject.toml

@@ -50,9 +50,7 @@ packages = [
 python = ">=3.8.0"
 aiohttp = "^3"
 asgiref = "^3"
-backports-datetime-fromisoformat = {version = "^1", python = "~3.6"}
 channels = "^3"
-dataclasses = {version = "^0.7", python = "~3.6"}
 Django = "^3"
 graphene = "^2.1"
 graphql-core = ">=2.2"
@@ -80,7 +78,6 @@ pytest-django = "*"
 pytest-pythonpath = "*"
 pytest-xdist = "*"
 tox = "*"
-types-dataclasses = {version = "*", python = "~3.6"}
 
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