deps: update dependency com.google.cloud.tools:dependencies-parent to v1.5.15 (#7072)

Author: renovate-bot

dashboard/pom.xml

@@ -6,7 +6,7 @@
   <parent>
     <groupId>com.google.cloud.tools</groupId>
     <artifactId>dependencies-parent</artifactId>
-    <version>1.5.13</version>
+    <version>1.5.15</version>
     <relativePath/>
   </parent>
   <artifactId>google-cloud-bom-dashboard</artifactId>