bump: :lang markdown

jrblevin/markdown-mode@c765b73b37 -> jrblevin/markdown-mode@b1a862f016

- The workaround introduced aad7bc521f addressed an issue that was
  fixed upstream (jrblevin/markdown-mode@44f0e89534).

Ref: jrblevin/markdown-mode#578
Revert: aad7bc521f

modules/lang/markdown/config.el

@@ -26,10 +26,6 @@ capture, the end position, and the output buffer.")
         markdown-make-gfm-checkboxes-buttons t
         markdown-fontify-whole-heading-line t
 
-        ;; HACK Due to jrblevin/markdown-mode#578, invoking `imenu' throws a
-        ;;      'wrong-type-argument consp nil' error if you use native-comp.
-        markdown-nested-imenu-heading-index (not (ignore-errors (native-comp-available-p)))
-
         ;; `+markdown-compile' offers support for many transpilers (see
         ;; `+markdown-compile-functions'), which it tries until one succeeds.
         markdown-command #'+markdown-compile

modules/lang/markdown/packages.el

@@ -1,7 +1,7 @@
 ;; -*- no-byte-compile: t; -*-
 ;;; lang/markdown/packages.el
 
-(package! markdown-mode :pin "c765b73b370f0fcaaa3cee28b2be69652e2d2c39")
+(package! markdown-mode :pin "b1a862f0165b7bafe0f874738a55be1b1720dd7d")
 (package! markdown-toc :pin "3d724e518a897343b5ede0b976d6fb46c46bcc01")
 (package! edit-indirect :pin "f80f63822ffae78de38dbe72cacaeb1aaa96c732")