Add "release action" to AEPCore repo; bump up version to 3.0.0-beta3

[yangyansong-adbe]

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[yangyansong-adbe]

@sbenedicadb I didn't move scripts to the .github directory, since they're also used in Makefile which will help to verify versions/builds locally. Let me know if you still have any concerns about it.