Update README.md

Signed-off-by: Kenechukwu Akubue <kengoon19@gmail.com>

Author: kengoon

README.md

@@ -4,6 +4,7 @@
 [![Maven Central](https://img.shields.io/maven-central/v/io.github.simplejnius/sjfirebase.svg)](https://central.sonatype.com/artifact/io.github.simplejnius/sjfirebase)
 [![MIT](https://img.shields.io/badge/license-MIT-green)](https://mit-license.org/)
 [![Publish Release](https://github.com/SimpleJnius/sj-firebase-java/actions/workflows/publish-release.yaml/badge.svg)](https://github.com/SimpleJnius/sj-firebase-java/actions/workflows/publish-release.yaml)
+[![Publish Snapshot](https://github.com/SimpleJnius/sj-firebase-java/actions/workflows/publish-snapshot.yaml/badge.svg)](https://github.com/SimpleJnius/sj-firebase-java/actions/workflows/publish-snapshot.yaml)
 
 Port Firebase Java SDK to Python