feat: Add test status badge to README (#73)

Author: typotter

README.md

@@ -1,5 +1,8 @@
 # Eppo JVM common SDK
 
+[![Test and lint](https://github.com/Eppo-exp/sdk-common-jdk/actions/workflows/lint-test-sdk.yml/badge.svg)](https://github.com/Eppo-exp/sdk-common-jdk/actions/workflows/lint-test-sdk.yml)  
+[![Maven Central](https://maven-badges.herokuapp.com/maven-central/cloud.eppo/sdk-common-jvm/badge.svg)](https://maven-badges.herokuapp.com/maven-central/could.eppo/sdk-common-jvm)
+
 This is the common SDK for the Eppo JVM SDKs. It provides a set of classes and interfaces that are used by the SDKs to
 interact with the Eppo API. You should probably not use this library directly and instead use the [Android](https://github.com/Eppo-exp/android-sdk)
 or [JVM](https://github.com/Eppo-exp/java-server-sdk) SDKs.