Adjust configuration mypy

[SoloJacobs]

The strict flag enables the following flags (the precise list depends on the mypy version, see mypy --help):

--warn-unused-configs,
--disallow-any-generics,
--disallow-subclassing-any,
--disallow-untyped-calls,
--disallow-untyped-defs,
--disallow-incomplete-defs,
--check-untyped-defs,
--disallow-untyped-decorators,
--warn-redundant-casts,
--warn-unused-ignores,
--warn-return-any,
--no-implicit-reexport,
--strict-equality,
--extra-checks

This means mypy accepts the following code as valid:

import typing

def ignore_without_code() -> int:
    return "a"  # type: ignore

def redundant_expr(x: int) -> int:
    return 1 if isinstance(x, int) else 2

def possible_undefined(x: int) -> int:
    if x > 0:
        result = 1
    return result

def any_explicit(_x: typing.Any) -> None:
    pass

def any_expr() -> None:
    a = x  # type: ignore[name-defined]