[pyserial] Fix read_all return type to not include None (#15797)
#36327
| Job | Run time |
|---|---|
| 5m 10s | |
| 1m 18s | |
| 10s | |
| 1m 19s | |
| 5m 7s | |
| 1m 32s | |
| 1m 16s | |
| 1m 24s | |
| 1m 22s | |
| 1m 35s | |
| 1m 29s | |
| 1m 34s | |
| 1m 19s | |
| 1m 44s | |
| 1m 52s | |
| 1m 58s | |
| 1m 57s | |
| 1m 51s | |
| 1m 36s | |
| 4m 50s | |
| 1m 47s | |
| 2m 3s | |
| 2m 0s | |
| 1m 44s | |
| 1m 17s | |
| 4m 8s | |
| 1m 41s | |
| 1m 34s | |
| 9m 15s | |
| 5m 13s | |
| 1m 53s | |
| 1m 14s | |
| 1m 42s | |
| 1h 15m 54s |