Change default partial_only to true, fix dependency loading issue

Author: emilong

lib/erb_lint/linters/instance_variable.rb

@@ -7,7 +7,7 @@ class InstanceVariable < Linter
       include LinterRegistry
 
       class ConfigSchema < LinterConfig
-        property :partials_only, accepts: [true, false], default: false, reader: :partials_only?
+        property :partials_only, accepts: [true, false], default: true, reader: :partials_only?
       end
       self.config_schema = ConfigSchema
 

lib/erb_lint/linters/partial_instance_variable.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require_relative "instance_variable"
+
 module ERBLint
   module Linters
     # Checks for instance variables in partials only