If tag consists of 1 character, it is considered special characters

If tag consists of 1 character, it is considered special characters.

Steps to reproduce:

1. Sign in in to antarctical and click "Write article"
2. Enter any 1 letter or number in tag field, for example 1
3. Click "Create article"

Actual result: error message "Tag 1 should not contain special characters"
Expected result: no error message about tag

The same error message is if 2 last symbols in tag field is ", "[comma, space]