feat: test status badge in README (#89)

Author: typotter

README.md

@@ -1,5 +1,8 @@
 # Eppo Server-Side SDK for Java
 
+[![Test and lint SDK](https://github.com/Eppo-exp/java-server-sdk/actions/workflows/lint-test-sdk.yml/badge.svg)](https://github.com/Eppo-exp/java-server-sdk/actions/workflows/lint-test-sdk.yml)  
+[![Maven Central](https://maven-badges.herokuapp.com/maven-central/cloud.eppo/eppo-server-sdk/badge.svg)](https://maven-badges.herokuapp.com/maven-central/cloud.eppo/eppo-server-sdk)
+
 ## Usage
 
 ### build.gradle: