[ci] update sonatype staging url

Our namespace was migrated to central.sonatype.com uploading to
oss.sonatype.org is no longer possible.

Author: line-o

exist-parent/pom.xml

@@ -1231,7 +1231,7 @@
         <repository>
             <id>sonatype-nexus-staging</id>
             <name>Nexus Release Repository</name>
-            <url>https://oss.sonatype.org/service/local/staging/deploy/maven2/</url>
+            <url>https://ossrh-staging-api.central.sonatype.com/service/local/staging/deploy/maven2/</url>
         </repository>
     </distributionManagement>