test:重命名测试类并更新文件名

- 将 PublicClientTests.java 重命名为 PkceClientTests.java
- 更新类名从 pkceClientTests 到 PkceClientTests

Author: chensoul

my-samples/auth-server-02-pkce/src/test/java/com/chensoul/PublicClientTests.java renamed to my-samples/auth-server-02-pkce/src/test/java/com/chensoul/PkceClientTests.java

@@ -26,7 +26,7 @@
  * @author Steve Riesenberg
  */
 @ExtendWith(SpringTestContextExtension.class)
-public class pkceClientTests {
+public class PkceClientTests {
     public final SpringTestContext spring = new SpringTestContext(this);
 
     @Autowired