fix readthedocs build to not require user input for towncrier build
#3349
| Job | Run time |
|---|---|
| 14s | |
| 0s | |
| 9s | |
| 2m 19s | |
| 2m 47s | |
| 2m 2s | |
| 2m 5s | |
| 6s | |
| 6s | |
| 5s | |
| 5s | |
| 6s | |
| 1m 7s | |
| 3m 8s | |
| 40s | |
| 1m 26s | |
| 1m 46s | |
| 1m 25s | |
| 1m 41s | |
| 1m 38s | |
| 1m 10s | |
| 1m 1s | |
| 2m 8s | |
| 27m 14s |