Upgrade PMD to 7.0.0-rc4

Add support for Java 21.

https://docs.pmd-code.org/pmd-doc-7.0.0-rc4/pmd_release_notes.html

Signed-off-by: Holger Friedrich <mail@holger-friedrich.de>

custom-checks/pmd/src/test/resources/pmd/ruleset/customrules.xml

@@ -1,5 +1,5 @@
 <ruleset name="Classpath Ruleset" xmlns="http://pmd.sourceforge.net/ruleset/2.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.net/ruleset_2_0_0.xsd">
   <description>Rule set that contains custom defined rules regarding the .classpath files</description>
-  <rule class="org.openhab.tools.analysis.pmd.UseSLF4JLoggerRule" name="UseSLF4JLoggerRule"/>
+  <rule class="org.openhab.tools.analysis.pmd.UseSLF4JLoggerRule" name="UseSLF4JLoggerRule" language="java"/>
 </ruleset>

pom.xml

@@ -67,7 +67,7 @@
     <commons.lang3.version>3.12.0</commons.lang3.version>
     <mockito.version>4.10.0</mockito.version>
     <maven.resources.version>3.3.0</maven.resources.version>
-    <pmd.version>6.53.0</pmd.version>
+    <pmd.version>7.0.0-rc4</pmd.version>
     <checkstyle.version>10.6.0</checkstyle.version>
     <spotbugs.version>4.7.3</spotbugs.version>
     <maven.core.version>3.6.0</maven.core.version>

sat-plugin/src/main/java/org/openhab/tools/analysis/tools/PmdChecker.java

@@ -60,7 +60,7 @@ public class PmdChecker extends AbstractChecker {
     /**
      * The version of the maven-pmd-plugin that will be used
      */
-    @Parameter(property = "maven.pmd.version", defaultValue = "3.20.0")
+    @Parameter(property = "maven.pmd.version", defaultValue = "3.21.2")
     private String mavenPmdVersion;
 
     /**