Running action in self-hosted runner

**Bug description**

When using game-ci/unity-builder@v2 on self-hosted linux docker machine some error occurs:
/bin/bash: /entrypoint.sh: Is a directory
Error: The process '/usr/bin/docker' failed with exit code 126

**How to reproduce**

1. Use this repo https://github.com/myoung34/docker-github-actions-runner and run https://github.com/myoung34/docker-github-actions-runner/wiki/Usage docker-compose with correct envs for repo (REPO_URL, ACCESS_TOKEN);
1.1. Optionally, if docker running on Windows bind volumes like this
volumes:
- //var/run/docker.sock:/var/run/docker.sock
3. See successfully started runner status and trigger action;
4. When step into build see errors.
-

**Expected behavior**

Run and build

**Additional details**

--volume /_work/_actions/game-ci/unity-builder/v2.1.2/dist/platforms/ubuntu/entrypoint.sh:/entrypoint.sh:z unityci/editor:ubuntu-2020.3.28f1-android-1
maybe this line broken?