Strip diacritics for pymorphy lemmatizer

[adrianeboyd]

Description

Strip diacritics for pymorphy lemmatizer.

Types of change

Enhancement.

Checklist

• [x] I confirm that I have the right to submit this contribution under the project's MIT license.
• [x] I ran the tests, and all new and existing tests passed.
• [x] My changes don't require a change to the documentation, or if they do, I've added all required information.