fix: use lxml 5 (ietf-tools#8279)

Author: rjsparks

requirements.txt

@@ -39,7 +39,8 @@ jsonfield>=3.1.0    # for SubmissionCheck.  This is https://github.com/bradjaspe
 jsonschema[format]>=4.2.1
 jwcrypto>=1.2    # for signed notifications - this is aspirational, and is not really used.
 logging_tree>=1.9    # Used only by the showloggers management command
-lxml>=4.8.0,<5
+lxml>=5.3.0    # lxml[html_clean] fails on some architectures
+lxml_html_clean>=0.4.1
 markdown>=3.3.6
 types-markdown>=3.3.6
 mock>=4.0.3    # Used only by tests, of course