Ensure response codes in tests are integers.

In rails 5 this was somehow making it through as a string, but this
`to_i` call simply fixes that.

Author: Sam Phippen

lib/rspec/rails/matchers/have_http_status.rb

@@ -85,7 +85,7 @@ def initialize(code)
           # @return [Boolean] `true` if the numeric code matched the `response` code
           def matches?(response)
             test_response = as_test_response(response)
-            @actual = test_response.response_code
+            @actual = test_response.response_code.to_i
             expected == @actual
           rescue TypeError => _ignored
             @invalid_response = response