Flarestack

The `DESYSubmitter` can now do manual submission (see [this](https://github.com/icecube/flarestack/commit/d22e2e4efdd51a9734073fbed4c43feff7e7b3a6)). Also revamped the [documentation](https://flarestack.readthedocs.io/en/latest/?badge=latest).

What's Changed
`flarestack` is now `black`. The coding style is implemented and checked for in an updated CI pipeline.
[Some small changes](https://github.com/icecube/flarestack/commit/5d166f4e0d28265759815b63d92bbc2b5ccdf126) make the `ResultHandler` more flexible. It's now easier to [inject different sources than the ones used in the llc fit](https://github.com/icecube/flarestack/commit/318687755ea6f2ac1ad659edd865c7631ad9b27b).
The main difference to `v2.4.2` is that

**Full Changelog**: https://github.com/icecube/flarestack/compare/v2.4.1...v2.4.2

New release of flarestack. Relative to the previous release (v2.3.0), the major change is that Travis-CI integration has been completely deprecated. Instead, Github Actions are used to unit tests, coverage and deployment.

v2.4.0 was inadvertantly published to Pypi prematurely, but from now on all new tagged releases (and only tagged releases) will be automatically deployed.

New release of Flarestack v2 (Titan). The key change versus the previous release (v2.2.6) is the incorporation of specified versions for all python package dependencies in *setup.py*, ensuring better reproducibility in future. Going forward, these dependencies will be managed/updated by Dependabot.

In addition there were minor changes to replace use of `np.float/np.bool`, addressing deprecation warnings.

The main changes to V2.2.5 are
* the time PDF DecayPDF is fixed now (the weighting for injection was not done right in DecayPDF.effective_injection_time())
* the submission script that is produced to submit jobs to the DESY cluster has been moved to the scratch space
* the Point Source Tracks v002_p03 are now implemented
* the get_rate() function in cosmo/rates/ can now give the uncertainty of the rate where available
* all the analysis scripts for the correction of the supernova stacking analysis are updated

New release of Flarestack v2 (Titan), containing fix of bug that had prevented use of the cluster search method.