Update dependency org.apache.sling:org.apache.sling.models.impl to v1.7.8

Author: renovate[bot]

tooling/conga-aem-maven-plugin/src/it/wcmio-archetype-aem65/parent/pom.xml

@@ -89,7 +89,7 @@
       <dependency>
         <groupId>org.apache.sling</groupId>
         <artifactId>org.apache.sling.models.impl</artifactId>
-        <version>1.6.4</version>
+        <version>1.7.8</version>
       </dependency>
 
       <!-- Latest Sling Context-Aware Configuration bundles -->