chore: Update prost, prost-derive and prost-build to 0.12
#690
| Job | Run time |
|---|---|
| 4m 34s | |
| 2m 26s | |
| 2m 4s | |
| 1m 5s | |
| 1m 50s | |
| 3m 26s | |
| 1m 59s | |
| 1m 27s | |
| 3m 34s | |
| 1m 23s | |
| 3m 8s | |
| 3m 27s | |
| 1m 28s | |
| 4m 25s | |
| 5m 30s | |
| 5m 16s | |
| 2m 5s | |
| 2m 2s | |
| 1m 51s | |
| 2m 3s | |
| 5m 47s | |
| 5m 37s | |
| 1h 6m 27s |