www/py-bleach: Update to 1.4

• Update to 1.4
• Switch from GITHUB to CHEESESHOP for MASTER_SITES
• Add BUILD_DEPENDS on six
• Update minimum version for html5lib RUN_DEPENDS
• Add TESTS option and tweak existing QA/Test entries
• Modernize Python framework entries
• Add LICENSE_FILE

Changes:

• https://github.com/jsocol/bleach/blob/v1.4/CHANGES

PR: 146461
Submitted by: Muhammad Rahman <5u623l20 at gmail dotcom> (with changes)