What's Changed
* Adding Swarm FAST L2 TEC collections by smithara in https://github.com/ESA-VirES/VirES-Python-Client/pull/122
* Fix concatenation of datasets when some are empty by smithara in https://github.com/ESA-VirES/VirES-Python-Client/pull/123
**Full Changelog**: https://github.com/ESA-VirES/VirES-Python-Client/compare/v0.12.2...v0.12.3
See https://viresclient.readthedocs.io/en/latest/release_notes.html