configure external links to open in a new tab

[gregcaporaso]

This, in _config.yml, isn't working:

parse:
  myst_links_external_new_tab: true

I also don't seem to be able to change other variables from their defaults, such as:

parse:
  myst_all_links_external: true

based on this logging output after running make clean && make html:

myst v0.18.1: MdParserConfig(commonmark_only=False,
  gfm_only=False,
  enable_extensions=['colon_fence', 'dollarmath', 'linkify', 'substitution', 'tasklist'],
  disable_syntax=[],
  all_links_external=False,
  url_schemes=['mailto', 'http', 'https'],
  ref_domains=None,
  highlight_code_blocks=True,
  number_code_blocks=[],
  title_to_header=False,
  heading_anchors=None,
  heading_slug_func=None,
  footnote_transition=True,
  words_per_minute=200,
  sub_delimiters=('{', '}'),
  linkify_fuzzy_links=True,
  dmath_allow_labels=True,
  dmath_allow_space=True,
  dmath_allow_digits=True,
  dmath_double_inline=False,
  update_mathjax=True,
  mathjax_classes='tex2jax_process|mathjax_process|math|output_area')

The same behavior was observed when building with myst-parser 2.0.0.

(I don't want to overwrite myst_all_links_external - just testing.)