improve client declaration in the test

Remove num param

Summary of changes:
- Upgraded Java target to version 21.
- Updated Gradle wrapper to version 8.5 for Java 21 compatibility.
- Refactored SerpApi.java to remove incorrect inheritance from Exception.
- Updated GitHub Actions workflow to use Java 21 and gradle-setup-java action.
- Switched environment variable for API keys to SERPAPI_KEY in tests and CI.
- Reorganized tests: moved engine examples to src/test/java/serpapi/example/.
- Fixed failures in LocationApiTest and GoogleReverseImageTest.

…mand to use Gradle wrapper

…version changes

…P handling

- Updated JaCoCo configuration in build.gradle for better test coverage reporting.
- Refactored SerpApiHttp to utilize HttpClient for HTTP requests, improving performance and readability.
- Adjusted Makefile and demo Makefile to use the Gradle wrapper consistently.
- Added a new test class for Google Local Services to validate API functionality.
- Updated existing tests to ensure they handle null API keys gracefully.

update gradlew wrapper

upgrade gradle version

…ration

- Updated JaCoCo tool version for enhanced test coverage reporting.
- Fixed syntax for Maven repository URL.
- Added exclusions in test configuration to avoid instrumenting JDK internals.
- Updated HashMap instantiation in SerpApi.java for type safety.