fix warning color in email

tester.py

@@ -238,6 +238,7 @@ class Tester():
         html_report = html_report.replace('\033[91m', '<span style="color: red;">')
         html_report = html_report.replace('\033[92m', '<span style="color: green;">')
         html_report = html_report.replace('\033[94m', '<span style="color: blue;">')
+        html_report = html_report.replace('\033[93m', '<span style="color: yellow;">')
         html_report = html_report.replace('\033[0m', '</span>')
         # Store locally results
         now = datetime.datetime.utcnow()