Support for old agones

[XAMPPRocky]

This is just a PR to get a version for older agones, shouldn't be merged.

[XAMPPRocky]

Hmm why is agones still failing 🤔

[quilkin-bot]

Build Succeeded :partying_face:

Build Id: bb6112ba-78ba-4010-8f24-e3aede2cb5bc

The following development images have been built, and will exist for the next 30 days:

• us-docker.pkg.dev/quilkin/ci/quilkin:0.9.0-dev-4328939

To build this version:

git fetch [email protected]:googleforgames/quilkin.git pull/954/head:pr_954 && git checkout pr_954
cargo build