Update haml gem to 5.2.0

[Hamms]

Switching us back to the mainline gem, from our custom fork. All modifications we made to our custom fork were accepted into the mainline gem as part of the 5.1.0 release.

Links

Original Issues

• Javascript escaping invalid, generates SyntaxError: expected expression, got '&' haml/haml#940
• FrozenError - can't modify frozen String haml/haml#982
• undefined method rstrip' for nil:NilClass (NoMethodError)` on empty :javascript filter block haml/haml#985

Fix PRs

• add escape_filter_interpolations option haml/haml#984
• fix error on empty :javascript and :css filter blocks haml/haml#986
• un-freeze TempleEngine precompiled string literals haml/haml#983

Testing story

Relying on existing unit tests.

PR Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[sureshc]

This looks like a simple change to me, but maybe teams that depend on our usage of HAML should take a look as well? Possibly Foundations, since we may do localization within HAML?