Deploy to GitHub Packages without the Sonatype staging plugin

Changes:
- Removed nexus-staging-maven-plugin, which took over mvn deploy and failed for lack of Sonatype credentials

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: akwirick

pom.xml

@@ -220,17 +220,6 @@
             <doclint>all</doclint>
           </configuration>
         </plugin>
-        <plugin>
-          <groupId>org.sonatype.plugins</groupId>
-          <artifactId>nexus-staging-maven-plugin</artifactId>
-          <version>1.6.13</version>
-          <extensions>true</extensions>
-          <configuration>
-            <serverId>sonatype-nexus-staging</serverId>
-            <nexusUrl>https://oss.sonatype.org/</nexusUrl>
-            <autoReleaseAfterClose>true</autoReleaseAfterClose>
-          </configuration>
-        </plugin>
         <plugin>
           <groupId>org.codehaus.mojo</groupId>
           <artifactId>animal-sniffer-maven-plugin</artifactId>
@@ -271,10 +260,6 @@
           <goals>deploy</goals>
         </configuration>
       </plugin>
-      <plugin>
-        <groupId>org.sonatype.plugins</groupId>
-        <artifactId>nexus-staging-maven-plugin</artifactId>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-project-info-reports-plugin</artifactId>