Fix Dependabot directory configuration

Dependabot was failing to find the Maven `pom.xml` because it was configured to look in the root directory `/`. The root `pom.xml` was moved to `org.moreunit.build/pom.xml` previously.

This commit updates `.github/dependabot.yml` to set the `directory` to `/org.moreunit.build` for the `maven` ecosystem so that Dependabot can successfully analyze and update Maven dependencies again.

Co-authored-by: RoiSoleil <3462260+RoiSoleil@users.noreply.github.com>

Author: google-labs-jules[bot]

.github/dependabot.yml

@@ -1,7 +1,7 @@
 version: 2
 updates:
 - package-ecosystem: maven
-  directory: /
+  directory: /org.moreunit.build
   schedule:
     interval: daily
   open-pull-requests-limit: 10