Fix tests warnings for BeautifulSoup and timezone naive datetimes

Patches from Rong Fu rong.fu.cn@windriver.com, thanks to him!

This patch adds the "tzinfo=timezone.utc" for datetime to make it as "aware datetime" in test_email.py

This patch also fixes the warnings for BeautifulSoup with parameter "lxml" which uses the HTML parser mode of the lxml library, not the XML parser.• This is fine for parsing HTML documents, but when trying to parse an XML document, the parser may not handle certain XML-specific features properly, leading to the XMLParsedAsHTMLWarning.