Update dependency npm to v9.6.0 (#335)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

pom.xml

@@ -18,7 +18,7 @@
     <tagNameFormat>@{project.version}</tagNameFormat>
     <useBeta>true</useBeta>
     <node.version>18.14.2</node.version>
-    <npm.version>9.5.1</npm.version>
+    <npm.version>9.6.0</npm.version>
   </properties>
   <name>Dark Theme</name>
   <url>https://github.com/jenkinsci/${project.artifactId}-plugin</url>