Add meta-unsupported-ansible rule for checking requires_ansible values

[alisonlhart]

Adding rule to check that the requires_ansible variable in meta/runtime.yml is set to a supported version of ansible-core.

Example error:

---
requires_ansible: ">=2.9.0"  <---- not a supported version of ansible

Example pass:

---
requires_ansible: ">=2.9.10"  <---- a supported version of ansible

Fixes #2102

[SRv6d]

This rule breaks version numbers that omit the patch version.
Omitting the patch version is common practice and even suggested in the docs.
If this was an intentional decision, it should at least be documented.

[alisonlhart]

@ssbarnea RE: comment above - There's an argument to be had for omitting the patch version requirement. However, as far as I can see, the only instance needed for omitting patch version is for compatibility with prerelease versions of Ansible. As stated in the docs: Ansible deviates from PEP440 behavior by truncating prerelease segments from the Ansible version. Ansible 2.11.0b1 is compatible with something that requires_ansible: ">=2.11".

So, since the intention of the shared profile is best practices for building useful content to be shared on Galaxy, Automation Hub, and private instances, I would argue there's not really an instance where using a patch version specifier would be an issue, unless you think the above would be a valid reason to change it.

I would say it's ideal to always specify patch versions, but again, I could see the benefit with removing it.