When using fence mode, securityLevel will not be set

[evan361425]

mkdocs.yaml:

markdown_extensions:
- pymdownx.superfences:
    custom_fences:
    - name: mermaid
      class: mermaid
      format: !!python/name:mermaid2.fence_mermaid_custom
plugins:
- mermaid2:
    arguments:
      securityLevel: loose

when using above config, the dialog will not support html:

flowchart
  A[long<br>text] --> B

My currently workaround will be set theme by JS and disable the fence method.
However this method will cause the theme of dialog not changed after changing the theme of site (as document mentioned).

markdown_extensions:
# remove below setting
# - pymdownx.superfences:
plugins
- mermaid2:
    arguments:
      securityLevel: loose
      theme: |
        ^(JSON.parse(__md_get("__palette").index == 1)) ? 'dark' : 'light'

[github-actions]

Thank you for your contribution! This is very appreciated.