java: Fix release credentials

Author: mpkorstanje

.github/workflows/release-mvn.yml

@@ -20,6 +20,6 @@ jobs:
         with:
           gpg-private-key: ${{ secrets.GPG_PRIVATE_KEY }}
           gpg-passphrase: ${{ secrets.GPG_PASSPHRASE }}
-          nexus-username: cukebot
+          nexus-username: ${{ secrets.SONATYPE_USERNAME }}
           nexus-password: ${{ secrets.SONATYPE_PASSWORD }}
           working-directory: java