mypy v0.9XX issues

[itdependsnetworks]

Mypy 0.9XX is resulting in linter failures.

root@93107d63fc67:/github/nornir# make mypy
poetry run mypy nornir tests
nornir/core/__init__.py:61: error: Parse error before **
nornir/core/__init__.py:68: error: Parse error before **
nornir/core/__init__.py:172: error: Parse error before string literal
Makefile:33: recipe for target 'mypy' failed
make: *** [mypy] Error 1
root@93107d63fc67:/github/nornir#

Here is the relevant code that is causing the linter to fail, in case that is of use.

class Nornir(object):
    def with_processors(self, processors: List[Processor]) -> "Nornir":
        return Nornir(**{**self.__dict__, **{"processors": Processors(processors)}})

    def with_runner(self, runner: RunnerPlugin) -> "Nornir":
        return Nornir(**{**self.__dict__, **{"runner": runner}})

    @classmethod
    def validate(cls, v):
        if not isinstance(v, cls):
            raise ValueError(f"Nornir: Nornir expected not {type(v)}")
        return v

I am not that familiar with mypy, and a quick google search and review of release notes did not immediately point to any issue.

I have confirmed that running mypy with 0.812 did not result in any issues.

[ktbyers]

Let's pin mypy version to 0.812 in pyproject.toml.

Then we can periodical update the dev dependencies on the cadence we choose (as opposed to just having the build randomly break).

[ktbyers]

If you want to do that in your ruamel PR, then I can review/merge it.

[dbarrosop]

There was an issue with mypy 0.900 as we had to install some stubs but couldn't reproduce the issue describe here. The CI for #694 couldn't either. I suspect the error might be that an unsupported version of python was being used.

In any case, #696 fixes mypy.