ci: use ubuntu-latest over deprecated ubuntu-20.04
#401
| Job | Run time |
|---|---|
| 30s | |
| 5m 18s | |
| 5m 31s | |
| 4m 50s | |
| 5m 11s | |
| 5m 19s | |
| 4m 56s | |
| 4m 25s | |
| 4m 28s | |
| 4m 10s | |
| 4m 29s | |
| 4m 33s | |
| 4m 44s | |
| 4m 59s | |
| 4m 37s | |
| 4m 35s | |
| 5m 2s | |
| 4m 52s | |
| 4m 39s | |
| 1h 27m 8s |