Release project, change project version to: 2.4.28.7

pom.xml

@@ -24,7 +24,7 @@
 
   <groupId>io.streamnative.connectors</groupId>
   <artifactId>pulsar-flink-connector_${scala.binary.version}</artifactId>
-  <version>2.4.28.6</version>
+  <version>2.4.28.7</version>
   <name>StreamNative :: Pulsar Flink Connector</name>
   <url>http://pulsar.apache.org</url>
   <inceptionYear>2019</inceptionYear>
@@ -385,6 +385,17 @@
               </gpgArguments>
             </configuration>
           </plugin>
+          <plugin>
+            <groupId>org.sonatype.plugins</groupId>
+            <artifactId>nexus-staging-maven-plugin</artifactId>
+            <version>1.6.8</version>
+            <extensions>true</extensions>
+            <configuration>
+              <serverId>ossrh</serverId>
+              <nexusUrl>https://oss.sonatype.org/</nexusUrl>
+              <autoReleaseAfterClose>true</autoReleaseAfterClose>
+            </configuration>
+          </plugin>
         </plugins>
       </build>
     </profile>