Start relying on data-canonical-lang in Banzai

glfm_specification/output_example_snapshots/html.yml

...specification/output_example_snapshots/snapshot_spec.html

glfm_specification/output_spec/spec.html

lib/banzai/filter/base_sanitization_filter.rb

lib/banzai/filter/code_language_filter.rb

lib/banzai/filter/kroki_filter.rb

lib/banzai/filter/math_filter.rb

lib/banzai/filter/mermaid_filter.rb

lib/banzai/filter/plantuml_filter.rb

lib/banzai/filter/syntax_highlight_filter.rb

lib/banzai/pipeline/ascii_doc_pipeline.rb

lib/banzai/pipeline/gfm_pipeline.rb

lib/banzai/pipeline/markup_pipeline.rb

spec/features/markdown/markdown_spec.rb

spec/lib/banzai/filter/code_language_filter_spec.rb

spec/lib/banzai/filter/kroki_filter_spec.rb

spec/lib/banzai/filter/math_filter_spec.rb

spec/lib/banzai/filter/mermaid_filter_spec.rb

spec/lib/banzai/filter/plantuml_filter_spec.rb

spec/lib/banzai/filter/suggestion_filter_spec.rb