Fix triggered jobs duration

[tommyknows]

Description

This commit fixes a bug where a glab ci status would panic if there is
a job within that CI pipeline that is not triggered yet. In such a case,
the StartedAt field is not populated, which triggered a panic.

To fix this, we use time.Now() if StartedAt is nil, which means that
the job will be displayed with a duration of 0.

Related Issue

Resolves #727

How Has This Been Tested?

Locally to a private gitlab instance which has triggered jobs.

Screenshots (if appropriate):

(failed) • 03m 47s      test            test
(success) • 01m 00s     test            my
(success) • 09m 37s     test            super
(success) • 00m 23s     test            jobs
(manual) • not started  test            triggered

https://privateinstance.com/myproject/-/pipelines/1
SHA: ...
Pipeline State: failed

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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)
• Documentation
• Chore (Related to CI or Packaging to platforms)

[profclems]

Thanks a lot @tommyknows...
This makes a lot of sense