chore: bump SDK version to 24.2.0

[TorstenDittmann]

This PR bumps SDK version metadata to 24.2.0 after the concurrent chunk upload update.

[greptile-apps]

Greptile Summary

This PR bumps the PHP SDK version from 24.1.0 to 24.2.0 by updating two header string literals in Client.php, following the concurrent chunk upload feature work.

• Updates user-agent and x-sdk-version headers from 24.1.0 to 24.2.0 in the default headers array.
• CHANGELOG.md does not yet have a 24.2.0 entry; consumers relying on it for release notes will find no record of the changes included in this version.

Confidence Score: 4/5

Safe to merge — the change is two version string updates with no logic impact.

The only change is bumping two version strings in the default headers array, which is straightforward and low-risk. The one minor gap is that CHANGELOG.md has no 24.2.0 section, so the release history will be incomplete unless that is added before or alongside tagging.

CHANGELOG.md is unchanged but lacks a 24.2.0 entry.

Important Files Changed

Filename	Overview
src/Appwrite/Client.php	Bumps user-agent header and x-sdk-version header value from 24.1.0 to 24.2.0; no logic changes.

_{Reviews (1): Last reviewed commit: "chore: bump SDK version to 24.2.0" | Re-trigger Greptile}