[RPM] Added Unit Tests

                       
| Q             | A   |
| ---           | --- |
| Bug fix?      | n   |
| New feature?  | y   |
| BC breaks?    | n   |
| Deprecations? | n   |
| Tests pass?   | n   |
| Fixed tickets | #14 |
| License       | MIT |
| Doc PR        | no  |
                       
Added Unit Tests to the following commands:

 * [x] IssueMilestoneListCommand
 * [x] IssueLabelListCommand

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