updates for keras_core / multi-backend support
#405
| Job | Run time |
|---|---|
| 6m 30s | |
| 12m 33s | |
| 11m 44s | |
| 14m 9s | |
| 10m 5s | |
| 9m 55s | |
| 6m 4s | |
| 7m 35s | |
| 2m 11s | |
| 7m 50s | |
| 6m 17s | |
| 8m 41s | |
| 7m 43s | |
| 9m 28s | |
| 2h 0m 45s |