Add test for canceling a completed job

Author: sshaw

spec/fixtures/cassettes/ShopifyAPI_GraphQL_Bulk/_cancel/raises_an_error_when_the_result_cannot_be_canceled.yml

@@ -86,6 +86,12 @@
       )
     end
 
+    it "raises an error when the result cannot be canceled" do
+      expect {
+        subject.cancel(ENV.fetch("BULK_SUCCESS_ID"))
+      }.to raise_error(ShopifyAPI::GraphQL::Bulk::Error, /cancel request failed/)
+    end
+
     # TODO
     # it "returns an Operation with the parsed partial result data" do
     # end