Use native node fetch API instead of node-fetch module

[hinricht]

Issue Report

Please use native node fetch API instead of node-fetch module.
We use repolinter and include a remote config via `extends, and are behind a coorporate Proxy, and node-fetch doesn't support proxy configurations.
We need to jump through several burning hoops to make it working (using proxychains i.e.).

Expected Behavior

We can use repolinter without any custom workaround behind a cooperate proxy and can include a remote config.

Actual Behavior

Repolinter: FAIL!
Linting repository "/Users/dj/repolintertest/genesis" with repolinter and pre-commit-tools image tag: 0.5.0
FetchError: request to https://raw.githubusercontent.com/todogroup/repolinter/main/rulesets/default.json failed, reason:

Steps to Reproduce the Issue

• Find a place with a (coorporate) proxy
• Export proxy env vars as usual
• Use this config

extends: https://raw.githubusercontent.com/todogroup/repolinter/main/rulesets/default.json

• Run repolinter

Additional resources

• https://blog.logrocket.com/fetch-api-node-js/