fix(theme-translations): fix invalid pluralization in cs

[Josh-Cena]

Motivation

Noticed in #7214 (comment)

This would currently log a warning because there are too many segments.

Have you read the Contributing Guidelines on pull requests?

Yes

[netlify]

✅ [V2]

Name	Link
🔨 Latest commit	0b2d40f
🔍 Latest deploy log	https://app.netlify.com/sites/docusaurus-2/deploys/626132f7ceebc60009852f1f
😎 Deploy Preview	https://deploy-preview-7222--docusaurus-2.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	60
🟢 Accessibility	100
🟢 Best practices	92
🟢 SEO	100
🟢 PWA	90

Lighthouse ran on https://deploy-preview-7222--docusaurus-2.netlify.app/

[github-actions]

Size Change: 0 B

Total Size: 799 kB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	50 kB
website/build/assets/css/styles.********.css	107 kB
website/build/assets/js/main.********.js	604 kB
website/build/index.html	38.8 kB

_{compressed-size-action}