packages/awscli-v2: Multiple updates and new versions for dependent package

[teaguesterling]

This addresses a few things that came up while adding a new version of the awscli-v2 package:

1. Adding a new version resulted in issues with the py-ruamel-yaml-clib, which is optional in python>=3.9
2. The post_install block failed due to (I suspect) changes to the spack API. Reordering the decorators fixed it.
3. The py-awscrt package was a strict version requirement, which was different than the previous version.
4. The py-awscrt package itself needed the required version. I also took the opportunity to add some new ones.
5. Added a list_url to make future updates easier.

[alalazo]

Waiting for @climbfuji review before merging

[climbfuji]

Thanks for these updates and for volunteering as a maintainer!