chore(deps): ignore incompatible updates for release/struts-6-8-x (#1497)

* chore(deps): ignore jetty-maven-plugin updates for release/struts-6-8-x

The jetty-maven-plugin 11.x is not compatible with Struts 6.8.x branch
which requires Java EE (not Jakarta EE). This prevents Dependabot from
creating incompatible update PRs like #1493.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

* chore(deps): also ignore caffeine updates for release/struts-6-8-x

Caffeine 3.x requires Java 11+ and uses jakarta.inject which is
incompatible with Struts 6.8.x. This prevents PRs like #1496.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

* chore(deps): also ignore jaxb-impl updates for release/struts-6-8-x

JAXB 4.x is the Jakarta EE version which is incompatible with
Struts 6.8.x (Java EE based). This prevents PRs like #1492.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

.github/dependabot.yml

@@ -14,3 +14,7 @@ updates:
     schedule:
       interval: "weekly"
     target-branch: "release/struts-6-8-x"
+    ignore:
+      - dependency-name: "org.eclipse.jetty:jetty-maven-plugin"
+      - dependency-name: "com.github.ben-manes.caffeine:caffeine"
+      - dependency-name: "com.sun.xml.bind:jaxb-impl"