Remove syntax incompatible with python 2

[HoussemNasri]

Closes #1373

Result of python -m compileall . ran with python 2.7.13 inside the atlassian directory

Listing . ...
Compiling .\__init__.py ...
Compiling .\bamboo.py ...
Listing .\bitbucket ...
Compiling .\bitbucket\__init__.py ...
Compiling .\bitbucket\base.py ...
Listing .\bitbucket\cloud ...
Compiling .\bitbucket\cloud\__init__.py ...
Compiling .\bitbucket\cloud\base.py ...
Listing .\bitbucket\cloud\common ...
Compiling .\bitbucket\cloud\common\__init__.py ...
Compiling .\bitbucket\cloud\common\builds.py ...
Compiling .\bitbucket\cloud\common\comments.py ...
Compiling .\bitbucket\cloud\common\users.py ...
Listing .\bitbucket\cloud\repositories ...
Compiling .\bitbucket\cloud\repositories\__init__.py ...
Compiling .\bitbucket\cloud\repositories\branchRestrictions.py ...
Compiling .\bitbucket\cloud\repositories\commits.py ...
Compiling .\bitbucket\cloud\repositories\defaultReviewers.py ...
Compiling .\bitbucket\cloud\repositories\deploymentEnvironments.py ...
Compiling .\bitbucket\cloud\repositories\diffstat.py ...
Compiling .\bitbucket\cloud\repositories\groupPermissions.py ...
Compiling .\bitbucket\cloud\repositories\hooks.py ...
Compiling .\bitbucket\cloud\repositories\issues.py ...
Compiling .\bitbucket\cloud\repositories\pipelines.py ...
Compiling .\bitbucket\cloud\repositories\pullRequests.py ...
Compiling .\bitbucket\cloud\repositories\refs.py ...
Compiling .\bitbucket\cloud\repositories\repositoryVariables.py ...
Listing .\bitbucket\cloud\workspaces ...
Compiling .\bitbucket\cloud\workspaces\__init__.py ...
Compiling .\bitbucket\cloud\workspaces\members.py ...
Compiling .\bitbucket\cloud\workspaces\permissions.py ...
Compiling .\bitbucket\cloud\workspaces\projects.py ...
Listing .\bitbucket\server ...
Compiling .\bitbucket\server\__init__.py ...
Compiling .\bitbucket\server\base.py ...
Listing .\bitbucket\server\common ...
Compiling .\bitbucket\server\common\__init__.py ...
Compiling .\bitbucket\server\common\permissions.py ...
Compiling .\bitbucket\server\globalPermissions.py ...
Listing .\bitbucket\server\projects ...
Compiling .\bitbucket\server\projects\__init__.py ...
Listing .\bitbucket\server\projects\repos ...
Compiling .\bitbucket\server\projects\repos\__init__.py ...
Compiling .\cloud_admin.py ...
Compiling .\confluence.py ...
Compiling .\crowd.py ...
Compiling .\errors.py ...
Compiling .\insight.py ...
Compiling .\jira.py ...
Compiling .\marketplace.py ...
Compiling .\portfolio.py ...
Compiling .\request_utils.py ...
Compiling .\rest_client.py ...
Compiling .\service_desk.py ...
Compiling .\statuspage.py ...
Compiling .\utils.py ...
Compiling .\xray.py ...

[gonchik]

Hi!
@HoussemNasri thank you for your PR. could. you adjust a bit black linter please ?

[HoussemNasri]

It seems we are blocked by this psf/black#1356 where even adding py27 to the target version would result in the insertion of a trailing comma. The issue was reported a while ago, but the maintainers didn't provide a fix unfortunately, and closed it saying that Python <3.5 reached EOL and thus wouldn't be supported in the newer versions of black. I didn't find a workaround either.

[Spacetown]

Instead of making it compatible 2.7 should be removed.

[HoussemNasri]

Instead of making it compatible 2.7 should be removed.

That's fine with me. We've already migrated our Python code to version 3.7. If the PR requires too much effort or doesn't align with the project's goals, feel free to close it.