(maint) Update version to 3.6.0 and update changelog for release

[span786]

What's this PR do?

This PR introduces the release of a new gem version, 3.6.0, which includes the latest updates and enhancements. The purpose of this release is to ensure that other projects can leverage these changes and stay aligned with the most recent improvements.

[span786]

The acceptance tests are failing because the system cannot download the puppet-agent due to the absence of a valid license. Below is the error snippet:

15:09:00 Last 10 lines of output were:
15:09:00 	No provider of 'puppet-agent=8.15.0.65.gd2a4b575d' found.
15:09:00 	+ '[' 104 -ne 0 ']'
15:09:00 	+ echo 'Failed to install puppet-agent. Please check that you have a PE license. Aborting...'
15:09:00 	Failed to install puppet-agent. Please check that you have a PE license. Aborting...
15:09:00 	+ exit 1
15:09:00 	+ remove_repo
15:09:00 	+ zypper rr puppet-enterprise
15:09:00 	Removing repository 'puppet-enterprise' [...done]
15:09:00 	Repository 'puppet-enterprise' has been removed.
15:09:00 	Error running install script /tmp/tmp.ruMXYdHTDz