Remove include of :google-ads-stubs-v7 in parent project (#571)

v7 support was removed from the library in release 17.0.0, but we missed
removing this line. As a result the artifacts published to Maven
include the v7 stubs library, even though v7 is no longer accessible
or supported in google-ads-java. For example, `GoogleAdsAllVersions`
no longer contains a `getVersion7()` method.

Author: jradcliff

settings.gradle

@@ -32,7 +32,6 @@ if (!startParameter.projectProperties.containsKey("release")) {
 
 // Keep the stubs modules at the end of this file. The stubs generator will
 // append new modules here as required. There should *not* be a newline at EOF.
-include ':google-ads-stubs-v7'
 include ':google-ads-stubs-v8'
 include ':google-ads-stubs-v9'
 include ':google-ads-stubs-v10'