Modify the Apollo version of the Apollo sample project

hippo4j-example/hippo4j-core-apollo-spring-boot-starter-example/pom.xml

@@ -47,7 +47,7 @@
         <dependency>
             <groupId>com.ctrip.framework.apollo</groupId>
             <artifactId>apollo-client</artifactId>
-            <version>1.3.0</version>
+            <version>${apollo.version}</version>
         </dependency>
 
         <dependency>
@@ -56,6 +56,12 @@
             <version>2.2.5.RELEASE</version>
         </dependency>
 
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>1.7.21</version>
+        </dependency>
+
         <dependency>
             <groupId>io.micrometer</groupId>
             <artifactId>micrometer-registry-prometheus</artifactId>