FreeBSD: VID-9b7491fb-f253-11e9-a50c-000c29c4dc65 (CVE-2019-15903): python 3.7 -- multiple vulnerabilities

Python changelog: bpo-38243: Escape the server title of xmlrpc.server.DocXMLRPCServer when rendering the document page as HTML. bpo-38174: Update vendorized expat library version to 2.2.8, which resolves CVE-2019-15903. bpo-37764: Fixes email._header_value_parser.get_unstructured going into an infinite loop for a specific case in which the email header does not have trailing whitespace, and the case in which it contains an invalid encoded word. bpo-37461: Fix an infinite loop when parsing specially crafted email headers. bpo-34155: Fix parsing of invalid email addresses with more than one @ (e.g. a@[email protected].) to not return the part before 2nd @ as valid email address.