Switch from using hub to gh in GitHub actions

[amisevsk]

What does this PR do?

The hub CLI has been removed from the Ubuntu 20.04 runner and is intended to be replaced with the 'gh' CLI. This commit adapts the previous hub command to open a PR into a gh command that does the same.

A note on arguments:

• There's no -f (force, even if not all commits are pushed to remote) equivalent in gh. This shouldn't be an issue because the prior command is git push origin ${PR_BRANCH}
  • Instead, -f in gh means "create PR description from last commit", which should duplicate what the -m was doing in hub
• -b (base branch) and -h (head branch) are replaced with -B and -H

What issues does this PR fix or reference?

release GH action is failing.

Is it tested? How?

I haven't directly tested, will probably have to wait for the next release to see if everything works appropriately.

PR Checklist

• [ ] E2E tests pass (when PR is ready, comment /test v8-devworkspace-operator-e2e, v8-che-happy-path to trigger)
  • [ ] v8-devworkspace-operator-e2e: DevWorkspace e2e test
  • [ ] v8-che-happy-path: Happy path for verification integration with Che

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: amisevsk, AObuchow

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/devfile/devworkspace-operator/blob/main/OWNERS)~~ [amisevsk] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[AObuchow]

For some reason the check sources CI failed, the PR branch maybe wasn't based off of https://github.com/devfile/devworkspace-operator/pull/1180. Re-running it now

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (c654384) 52.96% compared to head (447af2e) 53.01%. Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1196 +/- ## ========================================== + Coverage 52.96% 53.01% +0.05% ========================================== Files 84 84 Lines 7583 7583 ========================================== + Hits 4016 4020 +4 + Misses 3278 3275 -3 + Partials 289 288 -1 ``` [see 1 file with indirect coverage changes](https://app.codecov.io/gh/devfile/devworkspace-operator/pull/1196/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=devfile)

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