chore: fix rubocop issues

lib/activerecord_spanner_adapter/base.rb

@@ -4,6 +4,7 @@
 # license that can be found in the LICENSE file or at
 # https://opensource.org/licenses/MIT.
 
+require "active_record/gem_version"
 require "activerecord_spanner_adapter/relation"
 
 module ActiveRecord
@@ -14,7 +15,7 @@ class TableMetadata # :nodoc:
   end
 
   class Base
-    VERSION_7_1 = Gem::Version.create('7.1.0')
+    VERSION_7_1 = Gem::Version.create "7.1.0"
 
     # Creates an object (or multiple objects) and saves it to the database. This method will use mutations instead
     # of DML if there is no active transaction, or if the active transaction has been created with the option
@@ -64,8 +65,12 @@ def self._insert_record values, returning = []
       end
       result = connection.insert(im, "#{self} Create", primary_key || false, primary_key_value)
 
-      return result if ActiveRecord::gem_version < VERSION_7_1
-      [result]
+      _convert_primary_key result
+    end
+
+    def self._convert_primary_key primary_key_value
+      return primary_key_value if ActiveRecord.gem_version < VERSION_7_1
+      [primary_key_value]
     end
 
     def self._upsert_record values
@@ -137,11 +142,9 @@ def self._buffer_record values, method
       mutation = Google::Cloud::Spanner::V1::Mutation.new(
         "#{method}": write
       )
-
       connection.current_spanner_transaction.buffer mutation
 
-      return primary_key_value if ActiveRecord::gem_version < VERSION_7_1
-      [primary_key_value]
+      _convert_primary_key primary_key_value
     end
 
     def self._set_composite_primary_key_values primary_key, values