Release 1.15.0 - A lot of things:

• Require fresh testcloud with coreos support
• Bad substitution in tmt-reboot
• Ignore "certificate verify failed" error when handling retries
• Cache content of each loaded environment file
• Initial polarion support for test export
• Fixes names of Artemis API versions
• Convert FmfIdType from TypedDict to a dataclass
• Add CoreOS support to the testcloud provision
• Run containers with root user
• Retry getting environment file
• Test import --general is default now
• Add typing for steps/finish/shell.py
• Enhance tmt.utils.retry_session with timeout support
• Adjust the rpm-ostree install implementation
• Add support for the rpm-ostree package manager
• Add environment-file to possible Plan keys
• Avoid Library url conflict if repo doesn't exist
• Check changes are pushed before export nitrate
• Add typing for beakerlib.py
• Unbundle template from the report.html plugin
• Rename uuid to identifier to prevent conflicts
• Use must for all mandatory spec requirements
• Fail import for packages starting with minus sign
• Adds support for newer Artemis API versions
• Disable the extra verbose progress in testcloud
• Refactor internal executor scripts
• Adds "missing" imports to help IDEs follow objects
• Add typing for steps/init.py
• Implement the test result attribute
• Add typing for plugins/init.py
• Detect legacy relevancy during import as well
• Implement the new user story key priority
• Implement new class SerializableContainer
• Add schema for stories
• Add typing for steps/prepare/shell.py
• Add typing for steps/prepare/ansible.py
• Require fmf >= 1.1.0 (we need validation support)
• Package fmf root into the source tarball as well
• Add JSON Schema for tests
• Exclude namespaced backup in beakerlib
• Use --depth=1 when cloning git repos by default
• Handle missing nitrate user during export
• Removes unused GuestContainer.container_id attribute
• Every subpackage must require the main tmt package
• Introduce dataclasses as a requirement
• Avoid re-using image/instance for different values by testcloud plugin
• Add typing for multihost.py
• Except nitrate xmlrpc issues during import
• Exclude beakerlib's backup dir from guest.pull()
• Increase duration for the reboot-related tests
• Several release-related tests and docs adjustments