refact(build): enabling build for release branch

[mynktl]

Why is this PR required? What issue does it fix?: As of now Travis build is triggered on master branch only, not on release branch. This PR address this issue.

What this PR does?: This PR enables travis build for release branch.

Does this PR require any upgrade changes?: No

If the changes in this PR are manually verified, list down the scenarios covered and commands you used for testing with logs:

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:

Signed-off-by: mayank mayank.patel@mayadata.io

[mynktl]

'll raise a cherry-pick to v1.10.x once this PR get merged.