fix(core/slider): fix tick color

[matthiashader]

💡 What is the current behavior?

• currently the tick-color of the ix-slider is color-7

GitHub Issue Number: #N/A

🆕 What is the new behavior?

• tick-color of the ix-slider is now color-8

🏁 Checklist

A pull request can only be merged if all of these conditions are met (where applicable):

• 🦮 Accessibility (a11y) features were implemented
• 🗺️ Internationalization (i18n) - no hard coded strings
• 📲 Responsiveness - components handle viewport changes and content overflow gracefully
• 📄 Documentation was reviewed/updated (yarn docs)
• 🧪 Unit tests were added/updated and pass (yarn test)
• 📸 Visual regression tests were added/updated and pass (yarn visual-regression)
• 🧐 Static code analysis passes (yarn lint)
• 🏗️ Successful compilation (yarn build, changes pushed)

👨‍💻 Help & support

[changeset-bot]

🦋 Changeset detected

Latest commit: 4bc6339

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@siemens/ix	Patch
@siemens/ix-angular	Patch
@siemens/ix-react	Patch
@siemens/ix-vue	Patch

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[danielleroux]

• PR description looks empty for me, please fill out.
• Changeset missing for version bump