SimilarSeriesForm: add tests

[0pdd]

The puzzle 1280-9a82bce8 from #1280 has to be resolved:

mystamps/src/main/frontend/src/components/SimilarSeriesForm.js

Line 6 in 1391152

// @todo #1280 SimilarSeriesForm: add tests

The puzzle was created by Slava Semushin on 12-Apr-20.

[php-coder]

This issue depends on #1484 where Jest and all required test dependencies will be added.