Fix Unity version on linux runner (#365)

* u3d version?

* more print out for u3d

Co-authored-by: Cynthia Jiang <[email protected]>

Author: cynthiajoan

scripts/gha/unity_installer.py

@@ -171,6 +171,7 @@ def install_unity(unity_version, platforms):
   package_csv = ",".join(filter(None.__ne__, package_list))
 
   u3d = find_u3d()
+  run([u3d, "available", "-u", unity_version], check=False)
   run([u3d, "available", "-u", unity_full_version, "-p"], check=False)
   run([u3d, "install", "--trace",
        "--verbose", unity_full_version,