(temporarily) use ewatercycle-HBV from ewatercycle org

Currently we use the pip ewatercycle-hbv package.
https://github.com/eWaterCycle/infra/blob/5fd4933792704f339a4ba44d8816cd0bcb788c15/roles/ewatercycle/templates/environment.yml.j2#L16-L18

However, some important patches were done in https://github.com/ewatercycle/ewatercycle-hbv and David does not have much time to work on this now.

@RolfHut wants to temporarily use the forked version, until the new TU Delft RSE can work on this

Todo:

- [x] temporarily point to ewatercycle/ewatercycle-hbv in environment.yml
- [ ] have new RSE take ownership of ewatercycle-hbv, and update the package in pypi
- [ ] use the pypi version again