fix(aws): handle AWS key-only tags

[MrCloudSec]

Description

Handle AWS Tags that only have keys and non-existing values so no KeyError can raise.

>>> tags = [{"Key": "name"}]
>>> unroll_tags(tags)
{'name': ''}

Checklist

• Are there new checks included in this PR? Yes / No
  • If so, do we need to update permissions for the provider? Please review this carefully.
• Review if the code is being covered by tests.
• Review if code is being documented following this specification https://github.com/google/styleguide/blob/gh-pages/pyguide.md#38-comments-and-docstrings

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.16%. Comparing base (c2552ee) to head (a0bc742).
Report is 558 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4845   +/-   ##
=======================================
  Coverage   89.16%   89.16%           
=======================================
  Files         933      933           
  Lines       28567    28567           
=======================================
  Hits        25473    25473           
  Misses       3094     3094           

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[jfagoagas]

Several questions:

• What is the origin of this issue?
• Does it need to be backported to v4.3 and v3?

[jfagoagas]

Great catch!

[github-actions]

💚 All backports created successfully

Status	Branch	Result
✅	v4.3

Questions ?

Please refer to the Backport tool documentation and see the Github Action logs for details