chore(react): change button color from secondary to primary in BaseSignOutButton

[brionmario]

Purpose

This pull request makes a minor UI update to the sign-out button in the @asgardeo/react package. The button color has been changed from secondary to primary to better align with the design system.

• Changed the color prop from "secondary" to "primary" in the BaseSignOutButton component (BaseSignOutButton.tsx).
• Documented the change in the changeset file .changeset/easy-colts-dream.md.

Related Issues

• chore: stabilize @asgardeo/react & @asgardeo/nextjs #81

Related PRs

• N/A

Checklist

• e2e cypress tests locally verified.
• Manual test round performed and verified.
• UX/UI review done on the final implementation.
• Documentation provided. (Add links if there are any)
• Unit tests provided. (Add links if there are any)
• Integration tests provided. (Add links if there are any)

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines?
• Ran FindSecurityBugs plugin and verified report?
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets?