librive.so requires GLIBC 2.38, breaks on Ubuntu 22.04 CI images

Environment

• Rive Unity: 0.4.2
• Unity: 6.4.0f1
• CI: GameCI (game-ci/unity-builder@v4), which uses an Ubuntu 22.04-based image (glibc 2.35)
• Target platforms: Android (Failing), iOS (Succeeding)

Issue
On our Linux CI, Unity throws a DllNotFoundException when loading librive.so during the Android build. The library is linked against glibc 2.38, but the GameCI image provides glibc 2.35.

Error
DllNotFoundException: /lib/x86_64-linux-gnu/libm.so.6: version `GLIBC_2.38' not found (required by /github/workspace/Packages/app.rive.rive-unity/Runtime/Libraries/Linux/x86_64/librive.so)

Why bumping the image isn't easy
Moving to Ubuntu 24.04 (glibc 2.39) would require building and hosting a custom Unity Editor image since GameCI doesn't ship one yet — a multi-day effort.

Ask
Would it be feasible to build librive.so against an older glibc (2.35 or earlier)? Ubuntu 22.04 is in LTS support until 2027 and is the current base for GameCI's Unity images, so this likely affects other users on Linux CI.

Start by examining the packaged Runtime/Libraries/Linux/x86_64/librive.so and how the Unity package builds or obtains it. Reproduce the Android build with game-ci/unity-builder@v4 on the Ubuntu 22.04 image, then verify that librive.so loads without requiring GLIBC_2.38.