run borg compact after each prune

[shivansh02]

Description

Automatically run borg compact after each borg prune if borg>=1.2.

Related Issue

#1718

Motivation and Context

Backup space usage is exploding for some people until they notice they have to click on "compact" manually. This is a quick fix for the problem, while proper compact scheduling is implemented.

How Has This Been Tested?

Tested by me locally. Manually pruned a repository and borg compact was run automatically.

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 read the CONTRIBUTING guide.
• 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 added tests to cover my changes.
• All new and existing tests passed.

I provide my contribution under the terms of the license of this repository and I affirm the Developer Certificate of Origin.