redo renku datasets

• refactor biweekly averages closes #5 (closed)
• use float32 only closes #3 (closed)
• recreate biweekly renku datasets, closes https://renkulab.io/gitlab/aaron.spring/s2s-ai-challenge/-/issues/22
• merge afterwards: https://renkulab.io/gitlab/tasko.olevski/s2s-ai-competition-scoring-image/-/merge_requests/3