Asteria v1.2.1

New rerelease for Flarestack v1 (Asteria), with updates for second unblinding of TDE analysis for AT2018cow. Includes new GFU v002_p04 data, as well as modifications of the data_loader to account for new field naming conventions (as detailed in https://wiki.icecube.wisc.edu/index.php/Nu_Sources_Datasets and documents within). This version of GFU is the clean version found in /data/ana/, without the minor 'events in good runs but outside good run period' bug. This release also includes a check for any future versions of this bug in other data samples. Other that the additional source, this release maintains the method for calculating sensitivities/discovery potentials, and unblinding data using a flare search method as used in https://github.com/IceCubeOpenSource/flarestack/releases/tag/v1.1.0 for the original unblinding.