Use _load_from_sql instead of send(:instantiate)

These are both private APIs, but _load_from_sql will give us even more
standard behaviour (this is what find_by_sql calls) including emitting
the instantiation.active_record notification.

This may be faster in some cases since _load_from_sql includes a fast
path for when an inheritance column isn't present.

Author: jhawthorn

lib/github/sql.rb

@@ -211,9 +211,11 @@ def models(klass)
       return [] if frozen?
 
       # Use select_all to retrieve hashes for each row instead of arrays of values.
-      @models = connection.
-        select_all(query, "#{klass.name} Load via #{self.class.name}").
-        map { |record| klass.send :instantiate, record }
+      result_set = connection.
+        select_all(query, "#{klass.name} Load via #{self.class.name}")
+
+      # This is a private Rails API and should ideally not be used
+      @models = klass._load_from_sql(result_set)
 
       retrieve_found_row_count
       freeze