feat(js): update Highlight JS from 9.12.0 to 9.15.6 (#1075)

Adds support for more languages like plaintext and SAS.

See https://github.com/highlightjs/highlight.js/blob/master/CHANGES.md

data/assets.toml

@@ -12,8 +12,8 @@
   sri = "sha256-CSXorXvZcTkaix6Yvo6HppcZGetbYMGWSFlBw8HfCJo="
   url = "https://cdnjs.cloudflare.com/ajax/libs/jquery/%s/jquery.min.js"
 [js.highlight]
-  version = "9.12.0"
-  sri = "sha256-/BfiIkHlHoVihZdc6TFuj7MmJ0TWcWsMXkeDFwhi0zw="
+  version = "9.15.6"
+  sri = "sha256-aYTdUrn6Ow1DDgh5JTc3aDGnnju48y/1c8s1dgkYPQ8="
   url = "https://cdnjs.cloudflare.com/ajax/libs/highlight.js/%s/highlight.min.js"
 [js.mathJax]
   version = "2.7.4"
@@ -87,6 +87,6 @@
   sri = "sha256-uL8LUd3zkI/lXvc/Hv/oOu8ld6RJcOZiUY/8c+I+3/o="
   url = "https://cdnjs.cloudflare.com/ajax/libs/instantsearch.js/%s/instantsearch-theme-algolia.min.css"
 [css.highlight]
-  version = "9.12.0"
+  version = "9.15.6"
   sri = ""  # No SRI as highlight style is determined at run time.
   url = "https://cdnjs.cloudflare.com/ajax/libs/highlight.js/%s/styles/%s.min.css"