registry: add github backend and test for Liquibase

[benberryallwood]

• Add the GitHub backend for Liquibase (github:liquibase/liquibase) to the registry
• Add a test to the registry for Liquibase (including Java as a dependency in test.tools)

[greptile-apps]

Greptile Summary

This PR promotes github:liquibase/liquibase to the primary backend for Liquibase in the registry (with the existing asdf plugin retained as a fallback) and adds a registry test entry.

• The github: backend entry follows the same pattern used by other tools in the registry (e.g. allure, gradle, jbang).
• The test configuration (cmd, expected, and tools = ["java"]) matches the convention used by other JVM-based tools such as gradle.toml and jbang.toml.

Confidence Score: 5/5

A small, well-scoped registry update that mirrors conventions already established by similar Java-based tools in the codebase.

The change adds a first-class GitHub backend for Liquibase and a properly structured test entry. Both follow the exact patterns used by comparable tools (gradle, jbang, android-sdk), and the fallback asdf backend is preserved, so there is no regression risk for existing users.

No files require special attention.

Important Files Changed

Filename	Overview
registry/liquibase.toml	Adds github:liquibase/liquibase as the preferred backend (ahead of the existing asdf fallback) and adds a test with the correct liquibase --version expected string and Java as a test-time dependency.

_{Reviews (1): Last reviewed commit: "registry: add java as required tool for ..." | Re-trigger Greptile}

[gemini-code-assist]

Code Review

This pull request updates the registry/liquibase.toml file by adding a GitHub backend source and defining a test configuration to verify the installation using the liquibase --version command, which also specifies a dependency on Java. I have no feedback to provide as there were no review comments to evaluate.