Bump to latest version of Unity

[JonathanPorta]

Also, added a comment to make it a little more clear where to get these values for future version bumps.

[JonathanPorta]

PR Review

Summary

This PR bumps the Unity installer script from 5.4.1f1 to 5.5.2f1 and adds comments pointing to the 2017 release metadata. The patch is syntactically fine, but it is no longer useful as a “latest Unity” update and should not be merged as current maintenance.

Findings

• Severity: Blocking
  Location: Scripts/install.sh
  Problem: The PR hardcodes Unity 5.5.2f1 with a release note dated 2/24/17.
  Why it matters: The PR title and intent are to bump to the latest Unity, but this branch is now a stale 2017 update. Merging it today would encode an obsolete installer target while giving the impression that the CI image is current.
  Suggested fix: Close this PR and create a fresh Unity upgrade branch with the currently intended Unity editor version, matching project settings/build scripts, and a successful install/build validation.

• Severity: Important
  Location: Scripts/install.sh
  Problem: The installer still downloads Unity packages over plain http://netstorage.unity3d.com/unity and then runs them through sudo installer.
  Why it matters: A privileged installer path should not rely on unauthenticated transport. Even though this predates the PR, any modern Unity bump should fix it rather than preserving the old pattern.
  Suggested fix: Use Unity’s current authenticated/HTTPS download mechanism or a pinned checksum/signature verification step before installation.

Test / Verification Notes

I inspected the PR metadata, changed installer script, nearby build script, repo history, and changed diff. Commands run:

• sh -n Scripts/install.sh Scripts/build.sh — passed.
• git diff --check origin/master...HEAD — passed.

I did not run the installer because it would download and install Unity system-wide with sudo installer, which is not appropriate in the review scratch environment.

Overall Recommendation

Needs changes before merge.

[JonathanPorta]

Closing as stale: this bumps the installer to Unity 5.5.2f1, which is a 2017 release, so it no longer functions as a meaningful "latest Unity" update. Merging it today would just encode an obsolete installer target while implying the CI image is current.