Update dictionary.rs

[alexkingnz]

Allow tabs as well as spaces in dictionary files.

E.g. the /etc/radcli/dictionary in libradcli4 package on debian, which I intend to use, uses tabs. Without this change, the client claims not to know about the "User-Name" ATTRIBUTE. With it, things work fine.

Thanks,
Alex

[MikhailMS]

Hello there @alexkingnz - thank you for your PR

Looks simple and could be merged straighaway, just one thing - would appreciate if you can change PR from master to development branch - I don't allow any changes to be made directly to master branch :)

Then I can review it together with the next things awaiting to get fixed on developemnt branch and prepare new release by the end of this week (or you can build directly from development until I deploy library to crates.io)

[MikhailMS]

It is now part of development branch and would be published as part of new release soon :)