Integrate jira's new REST API endpoint for labels

[mikeboiko]

Is your feature request related to a problem? Please describe. I use issue labels in my workflow. One of the features that I would like to use is to get a list of all labels that are currently used in a project.

Describe the solution you'd like Jira recently implemented this feature in their REST API. See links below: https://ecosystem.atlassian.net/browse/ACJIRA-788 https://developer.atlassian.com/cloud/jira/platform/rest/v3/?utm_source=%2Fcloud%2Fjira%2Fplatform%2Frest%2F&utm_medium=302#api-rest-api-3-label-get

Thanks so much for the great jira python tool!