chore(version): add 2.4.0 to upgrade matrix

[shubham14bajpai]

Signed-off-by: shubham shubham.bajpai@mayadata.io

What this PR does?:
This PR adds 2.4.0 to the upgrade matrix.

Any additional information for your reviewer? :
Mention if this PR is part of any design or a continuation of previous PRs

Checklist:

• Fixes #
• PR Title follows the convention of <type>(<scope>): <subject>
• Has the change log section been updated?
• Commit has unit tests
• Commit has integration tests
• (Optional) Are upgrade changes included in this PR? If not, mention the issue/PR to track:
• (Optional) If documentation changes are required, which issue on https://github.com/openebs/openebs-docs is used to track them:

[prateekpandey14]

lgtm