Fix Rubocop deprecated method warnings

* `Cop.all` is deprecated. Use `Registry.all` instead.
* `inspect_file` is deprecated. Use `investigate` instead.

lib/pronto/rubocop/patch_cop.rb

@@ -31,7 +31,7 @@ def processed_source
       end
 
       def registry
-        @registry ||= ::RuboCop::Cop::Registry.new(RuboCop::Cop::Cop.all)
+        @registry ||= ::RuboCop::Cop::Registry.new(RuboCop::Cop::Registry.all)
       end
 
       def rubocop_config
@@ -59,7 +59,8 @@ def path
 
       def offenses
         team
-          .inspect_file(processed_source)
+          .investigate(processed_source)
+          .offenses
           .sort
           .reject(&:disabled?)
       end

spec/pronto/rubocop/patch_cop_spec.rb

@@ -11,7 +11,8 @@
   let(:runner) { double :runner }
   let(:ast) { double :ast, each_node: nil }
   let(:processed_source) { double :processed_source, ast: ast }
-  let(:team) { double :team, inspect_file: [offense] }
+  let(:team) { double :team, investigate: offenses }
+  let(:offenses) { double :offenses, offenses: [offense] }
   let(:offense_location) { double :location, first_line: 42, last_line: 43 }
   let(:offense) { double :offense, disabled?: false, location: offense_location }
   let(:offense_line) { double :offense_line, message: 'Err' }