Dynamically shorten generated gradle file

The dependency section is not generated when no packages are given. This makes the config file easier to read for plugin-only configs.

sync/src/gradle.py

@@ -20,7 +20,7 @@ plugins {
     
     """ + '\n    '.join(f'id("{name}") version "{version}"' for name, version in plugins.items()) + """
 }
-
+""" + ("""
 repositories {
     maven {
         url=uri("http://""" + repo + """/releases")
@@ -65,4 +65,6 @@ tasks.register("downloadDependencies") {
         }
     }
 }
-"""
+""" if packages else """
+tasks.register("downloadDependencies") {}
+""")