Migrate to central-portal and bump up the version (#168)

Author: mit-aws

README.md

@@ -25,7 +25,7 @@ For more information on using the amazon-sqs-java-extended-client-lib, see our g
   <dependency>
     <groupId>com.amazonaws</groupId>
     <artifactId>amazon-sqs-java-extended-client-lib</artifactId>
-    <version>2.1.1</version>
+    <version>2.1.2</version>
     <type>jar</type>
   </dependency>
 ```   

pom.xml

@@ -6,7 +6,7 @@
 
   <groupId>com.amazonaws</groupId>
   <artifactId>amazon-sqs-java-extended-client-lib</artifactId>
-  <version>2.1.1</version>
+  <version>2.1.2</version>
   <packaging>jar</packaging>
   <name>Amazon SQS Extended Client Library for Java</name>
   <description>An extension to the Amazon SQS client that enables sending and receiving messages up to 2GB via Amazon S3.
@@ -136,14 +136,14 @@
         </executions>
       </plugin>
       <plugin>
-        <groupId>org.sonatype.plugins</groupId>
-        <artifactId>nexus-staging-maven-plugin</artifactId>
-        <version>1.6.13</version>
+        <groupId>org.sonatype.central</groupId>
+        <artifactId>central-publishing-maven-plugin</artifactId>
+        <version>0.7.0</version>
         <extensions>true</extensions>
         <configuration>
-          <serverId>ossrh</serverId>
-          <nexusUrl>https://aws.oss.sonatype.org</nexusUrl>
-          <autoReleaseAfterClose>true</autoReleaseAfterClose>
+          <publishingServerId>central</publishingServerId>
+          <autoPublish>false</autoPublish>
+          <centralSnapshotsUrl>https://central.sonatype.com/repository/maven-snapshots/</centralSnapshotsUrl>
         </configuration>
       </plugin>
     </plugins>
@@ -153,23 +153,12 @@
     <profile>
       <id>publishing</id>
 
-      <distributionManagement>
-        <snapshotRepository>
-          <id>ossrh</id>
-          <url>https://oss.sonatype.org/content/repositories/snapshots</url>
-        </snapshotRepository>
-        <repository>
-          <id>ossrh</id>
-          <url>https://oss.sonatype.org/service/local/staging/deploy/maven2/</url>
-        </repository>
-      </distributionManagement>
-
       <build>
         <plugins>
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-gpg-plugin</artifactId>
-            <version>3.1.0</version>
+            <version>3.2.7</version>
             <executions>
               <execution>
                 <id>sign-artifacts</id>