Update bitlyshortener to >=0.5.0 to prevent generating some invalid short URLs
### Impact
Due to a sudden upstream breaking change by Bitly, versions of `bitlyshortener` <0.5.0 can generate an invalid short URL when a vanity domain exists.
### Patches
Upgrading `bitlyshortener` to 0.5.0 or newer will prevent the generation of any such invalid short URLs.
### References
* Release notes
https://github.com/impredicative/bitlyshortener/releases