Dependency cleanup

[mjurbanski-reef]

Changes:

• Remove pytest, black dependencies from bittensor package requirements. They are now installed only if bittensor[dev] extras group is requested.
• Loosen up production dependency requirements.
• Configure Dependabot to detect outdated (in terms of security patches) production dependencies
• support ~= version specifier in check_compatiblity.sh

Dependabot has to be enabled in https://github.com/opentensor/bittensor/settings/security_analysis (please note config file has to be present in default branch for it to be considered by Dependabot).

It is recommended that applications use tools allowing for proper dependency locking e.g. pdm, pip-tools, poetry.

This change is still rather conservative, as it mostly unblocks only .patch versions to be updated.
In some packages with strong semver support (e.g. aiohttp) I opted to constrain only major version already.
In future we should be able to do just >=MAJOR.MINOR for most package that declare semver use and without known vulnerabilities, but for now I opted for safer route of taking one step at a time.