Priority key should be optional (#323)

Author: Sushisource

temporalio/lib/temporalio/priority.rb

@@ -77,7 +77,7 @@ def self.default
     # @param priority_key [Integer, nil] The priority key
     # @param fairness_key [String, nil] The fairness key
     # @param fairness_weight [Float, nil] The fairness weight
-    def initialize(priority_key:, fairness_key: nil, fairness_weight: nil)
+    def initialize(priority_key: nil, fairness_key: nil, fairness_weight: nil)
       super
     end
 

temporalio/sig/temporalio/priority.rbs

@@ -4,7 +4,7 @@ module Temporalio
     attr_reader fairness_key: String?
     attr_reader fairness_weight: Float?
 
-    def initialize: (priority_key: Integer?, ?fairness_key: String?, ?fairness_weight: Float?) -> void
+    def initialize: (?priority_key: Integer?, ?fairness_key: String?, ?fairness_weight: Float?) -> void
 
     def self._from_proto: (untyped) -> Priority