Update to kolibri-explore-plugin 7.8.0

Author: dbnicholson

app/gradle.properties

@@ -13,7 +13,7 @@ kolibriUrl=https://github.com/learningequality/kolibri/releases/download/v0.16.0
 
 # kolibri-explore-plugin version or wheel URL. The wheel URL is
 # preferred if both are set.
-exploreVersion=7.7.0
+exploreVersion=7.8.0
 exploreUrl=
 
 # apps-bundle.zip URL. If not set, the URL is derived from the explore