feat(ts): markup italic and strikethrough in nvim 0.9

Ref. sainnhe/gruvbox-material#195

colors/edge.vim

@@ -10,7 +10,7 @@
 let s:configuration = edge#get_configuration()
 let s:palette = edge#get_palette(s:configuration.style, s:configuration.dim_foreground, s:configuration.colors_override)
 let s:path = expand('<sfile>:p') " the path of this script
-let s:last_modified = 'Sat Mar  2 01:32:52 PM UTC 2024'
+let s:last_modified = 'Wed Mar 27 01:57:23 PM UTC 2024'
 let g:edge_loaded_file_types = []
 
 if !(exists('g:colors_name') && g:colors_name ==# 'edge' && s:configuration.better_performance)
@@ -1657,7 +1657,7 @@ highlight! link mkdDelimiter Grey
 highlight! link mkdId Green
 " }}}
 " nvim-treesitter/nvim-treesitter {{{
-if has('nvim-0.8.0')
+if has('nvim-0.8')
   highlight! link @markup.heading.1.markdown markdownH1
   highlight! link @markup.heading.2.markdown markdownH2
   highlight! link @markup.heading.3.markdown markdownH3
@@ -1670,6 +1670,10 @@ if has('nvim-0.8.0')
   highlight! link @markup.heading.4.marker.markdown @conceal
   highlight! link @markup.heading.5.marker.markdown @conceal
   highlight! link @markup.heading.6.marker.markdown @conceal
+  if !has('nvim-0.10')
+    call edge#highlight('@markup.italic', s:palette.none, s:palette.none, 'italic')
+    call edge#highlight('@markup.strikethrough', s:palette.none, s:palette.none, 'strikethrough')
+  endif
 endif
 " }}}
 " syn_end }}}