Remove microsphere-java-core dependency

Drops the direct `microsphere-java-core` dependency from `microsphere-spring-boot-core/pom.xml` because this module no longer needs to declare it explicitly. This keeps the POM leaner and avoids redundant dependency declarations.

Author: mercyblitz

microsphere-spring-boot-core/pom.xml

@@ -26,12 +26,6 @@
             <optional>true</optional>
         </dependency>
 
-        <!-- Microsphere Java Core -->
-        <dependency>
-            <groupId>io.github.microsphere-projects</groupId>
-            <artifactId>microsphere-java-core</artifactId>
-        </dependency>
-
         <!-- Microsphere Spring Context -->
         <dependency>
             <groupId>io.github.microsphere-projects</groupId>