Upgrade Sorbet and fix visibility violations

Gemfile.lock

@@ -85,14 +85,14 @@ GEM
       rubocop (>= 1)
     ruby-progressbar (1.13.0)
     ruby2_keywords (0.0.5)
-    sorbet (0.5.12194)
-      sorbet-static (= 0.5.12194)
-    sorbet-runtime (0.5.12194)
-    sorbet-static (0.5.12194-universal-darwin)
-    sorbet-static (0.5.12194-x86_64-linux)
-    sorbet-static-and-runtime (0.5.12194)
-      sorbet (= 0.5.12194)
-      sorbet-runtime (= 0.5.12194)
+    sorbet (0.5.12221)
+      sorbet-static (= 0.5.12221)
+    sorbet-runtime (0.5.12221)
+    sorbet-static (0.5.12221-universal-darwin)
+    sorbet-static (0.5.12221-x86_64-linux)
+    sorbet-static-and-runtime (0.5.12221)
+      sorbet (= 0.5.12221)
+      sorbet-runtime (= 0.5.12221)
     spoom (1.7.4)
       erubi (>= 1.10.0)
       prism (>= 0.28.0)

lib/ruby_indexer/lib/ruby_indexer/entry.rb

@@ -333,6 +333,7 @@ def signatures
     end
 
     class Method < Member
+      # @override
       #: Array[Signature]
       attr_reader :signatures
 

lib/ruby_lsp/base_server.rb

@@ -101,19 +101,6 @@ def start
       end
     end
 
-    #: -> void
-    def run_shutdown
-      @incoming_queue.clear
-      @outgoing_queue.clear
-      @incoming_queue.close
-      @outgoing_queue.close
-      @cancelled_requests.clear
-
-      @worker.terminate
-      @outgoing_dispatcher.terminate
-      @store.clear
-    end
-
     # This method is only intended to be used in tests! Pops the latest response that would be sent to the client
     #: -> untyped
     def pop_response
@@ -132,6 +119,21 @@ def process_message(message)
       raise AbstractMethodInvokedError
     end
 
+    #: -> void
+    def run_shutdown
+      @incoming_queue.clear
+      @outgoing_queue.clear
+      @incoming_queue.close
+      @outgoing_queue.close
+      @cancelled_requests.clear
+
+      @worker.terminate
+      @outgoing_dispatcher.terminate
+      @store.clear
+    end
+
+    private
+
     # @abstract
     #: -> void
     def shutdown