fix(pom): Update Maven Central publishing settings.

 - Switches from the expired RSA-4096 GnuPG key to my new EdDSA key.
 - Enables legacy mode for Javadoc generation, which is necessary to
   support the somewhat hacked-together JBoss Log Manager Embedded /
   non-Embedded hybrid support.
 - Updates the Maven Javadoc plugin to version 3.6.0.

Change-Id: Ic9ebb684e182a92d8b09f85cea829073ecdfd6d2
diff --git a/pom.xml b/pom.xml
index 67dd2ce..5cc6950 100644
--- a/pom.xml
+++ b/pom.xml
@@ -66,7 +66,7 @@
     <google-java-format.version>1.15.0</google-java-format.version>
     <jar-plugin.version>3.3.0</jar-plugin.version>
     <maven-gpg-plugin.version>3.1.0</maven-gpg-plugin.version>
-    <maven-javadoc-plugin.version>3.5.0</maven-javadoc-plugin.version>
+    <maven-javadoc-plugin.version>3.6.0</maven-javadoc-plugin.version>
     <maven-source-plugin.version>3.3.0</maven-source-plugin.version>
     <nexus-staging-plugin.version>1.6.13</nexus-staging-plugin.version>
     <spotless-plugin.version>2.39.0</spotless-plugin.version>
@@ -244,6 +244,9 @@
                 <goals>
                   <goal>jar</goal>
                 </goals>
+                <configuration>
+                  <legacyMode>true</legacyMode>
+                </configuration>
               </execution>
             </executions>
           </plugin>
@@ -253,7 +256,7 @@
             <artifactId>maven-gpg-plugin</artifactId>
             <version>${maven-gpg-plugin.version}</version>
             <configuration>
-              <keyname>code@mulk.eu</keyname>
+              <keyname>44DD0CEE515E547A0ABAB1D24F2E30DF0A270EFB</keyname>
             </configuration>
             <executions>
               <execution>