Output error messages in red text

[nao1215]

Is your feature request related to a problem? Please describe.

If the expected value does not match the obtained value, the following message appears. We want to display this message in red text to make it easier for users to understand the error content.

                Error:          Not equal: 
                                expected: true
                                actual  : false
                Test:           TestNewApp/Width_test
                Messages:       mismatched values for header 'Content-Type'. Expected image/png but received text/plain; charset=utf-8
                Name:           width,height is zero

Use fatih/color to change text color for cross-platform support.