Use uv as Nox backend and several related improvements
#645
| Job | Run time |
|---|---|
| 2m 20s | |
| 4m 59s | |
| 2m 23s | |
| 3m 56s | |
| 5m 36s | |
| 3m 58s | |
| 3m 51s | |
| 3m 50s | |
| 5m 21s | |
| 3m 29s | |
| 5m 52s | |
| 2m 55s | |
| 48m 30s |