There's a merged pull request on the void-packages repository

robotfindskitten: ignore beta releases
https://github.com/void-linux/void-packages/pull/20192

Description:
http://robotfindskitten.org/download/POSIX/

`1600003.248b` was released in 2003, `2.7182818.701` was released in 2013.

```
XBPS_UPDATE_CHECK_VERBOSE=1 ./xbps-src update-check robotfindskitten
using robotfindskitten/update overrides
fetching http://www.robotfindskitten.org
fetching http://robotfindskitten.org/download/POSIX/
found version 1.4142135.406
found version 1.7320508.406
found version 2.7182818.701
found version 1600003.248b
ignored 1600003.248b due to *b*
```