fix(i18n): typo in cs.json

[andrejsoucek]

[Koenkk]

I believe this should go via https://poeditor.com/join/project?hash=Az88waAhPd

[stale[bot]]

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[pano9000]

I have gone ahead and fixed this via poeditor: https://poeditor.com/projects/po_edit?per_page=20&id=494809&id_language=38&filter=&order=tdate&search=Hla%C5%A1en%C3%AD

not sure, when and how these translations will get pulled in though