Updating mypy to 0.770 raises new errors

[KingDarBoja]

If bumping mypy to 0.770, these erros will show up:

graphql\execution\executors\asyncio.py:56: error: Incompatible types in assignment (expression has type "AbstractEventLoop", variable has type "Optional[_UnixSelectorEventLoop]")
graphql\execution\executors\asyncio.py:67: error: Item "None" of "Optional[_UnixSelectorEventLoop]" has no attribute "run_until_complete"
graphql\utils\type_comparators.py:39: error: Argument 2 to "is_type_sub_type_of" has incompatible type "Union[GraphQLList, GraphQLObjectType, GraphQLScalarType, GraphQLInputObjectType, GraphQLInterfaceType]"; expected "GraphQLScalarType"
graphql\utils\type_comparators.py:39: error: Argument 3 to "is_type_sub_type_of" has incompatible type "Union[GraphQLList, GraphQLObjectType, GraphQLScalarType, GraphQLInputObjectType, GraphQLInterfaceType]"; expected "GraphQLScalarType"
graphql\utils\type_comparators.py:43: error: Argument 2 to "is_type_sub_type_of" has incompatible type "Union[GraphQLList, GraphQLObjectType, GraphQLScalarType, GraphQLInputObjectType, GraphQLInterfaceType]"; expected "GraphQLScalarType"
graphql\utils\type_comparators.py:57: error: Argument 1 to "is_possible_type" of "GraphQLSchema" has incompatible type "GraphQLScalarType"; expected "Union[GraphQLInterfaceType, GraphQLUnionType]"
graphql\utils\type_comparators.py:57: error: Argument 1 to "is_possible_type" of "GraphQLTypeMap" has incompatible type "GraphQLScalarType"; expected "Union[GraphQLInterfaceType, GraphQLUnionType]"
graphql\validation\rules\overlapping_fields_can_be_merged.py:708: error: Argument 1 to "do_types_conflict" has incompatible type "Union[GraphQLList, GraphQLObjectType, GraphQLScalarType, GraphQLInputObjectType, GraphQLInterfaceType]"; expected "GraphQLScalarType"
graphql\validation\rules\overlapping_fields_can_be_merged.py:708: error: Argument 2 to "do_types_conflict" has incompatible type "Union[GraphQLList, GraphQLObjectType, GraphQLScalarType, GraphQLInputObjectType, GraphQLInterfaceType]"; expected "GraphQLScalarType"
graphql\validation\rules\overlapping_fields_can_be_merged.py:713: error: Argument 1 to "do_types_conflict" has incompatible type "Union[GraphQLList, GraphQLObjectType, GraphQLScalarType, GraphQLInputObjectType, GraphQLInterfaceType]"; expected "GraphQLScalarType"
graphql\validation\rules\overlapping_fields_can_be_merged.py:713: error: Argument 2 to "do_types_conflict" has incompatible type "Union[GraphQLList, GraphQLObjectType, GraphQLScalarType, GraphQLInputObjectType, GraphQLInterfaceType]"; expected "GraphQLScalarType"

I will address these errors in a PR.

[KingDarBoja]

@Cito Those errors seem to be cause by the use of type as function argument (__init__) which confuses mypy with the builtin type. Renaming to _type solves this.

[Cito]

In core 3 I'm using type_ in such cases, and a prefix like _type to denote an unused argument. I think it's ok to rename this and make v2 and v3 more similar in that regard.