simplify install_keras(), fix arm mac install
#370
| Job | Run time |
|---|---|
| 7m 15s | |
| 16m 44s | |
| 17m 35s | |
| 9m 41s | |
| 15m 40s | |
| 15m 5s | |
| 7m 10s | |
| 8m 12s | |
| 11m 56s | |
| 14m 22s | |
| 13m 41s | |
| 10m 18s | |
| 7m 46s | |
| 7m 26s | |
| 7m 22s | |
| 8m 19s | |
| 2h 58m 32s |