Feat: Add Spring Boot AutoConfiguration

[vitinh0z]

Description

This PR introduces Spring Boot AutoConfiguration to the library. It automatically registers the GithubApiModule bean when the library is used in a Spring Boot application that has Jackson on the classpath.

Resolves

Closes #61

Changes

• Added optional dependencies for spring-boot-autoconfigure (v2.7.18 for Java 11 compatibility).
• Added GithubClientAutoConfiguration to conditionally register the GithubApiModule bean.
• Registered the configuration in META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports.
• Added GithubClientAutoConfigurationTest using ApplicationContextRunner to verify the behavior.

Verification

• Ran mvn clean install -DskipTests locally -> BUILD SUCCESS.
• Ran mvn test locally -> All tests passed.