feat: Support WinSeparator highlighting

This new highlight has been added in Neovim version 0.10 and is now used
instead of `VertSplit`.

Related to #311

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 -   Implement [highlight-blend](https://neovim.io/doc/user/syntax.html#highlight-blend) feature #251
 -   Added Rust lifetime highlights #289
 -   Reimplemented `*_default` colorschemes.
+-   Support `WinSeparator` highlight, introduced in Neovim >= 0.10, replacing `VertSplit`.
 
 ### Changes
 
@@ -23,6 +24,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 -   Closed #251
 -   Fixed darkened sidebars when disabling `options.sidebars.disabled`
 
+This new highlight has been added in Neovim version 0.10 and is now used
+instead of `VertSplit`.
+
+Related to #311
+
 ## [v1.0.1] - 23 July 2023
 
 ### What's New?

lua/github-theme/group/editor.lua

@@ -40,6 +40,7 @@ function M.get(spec, config)
     -- TermCursorNC    = {}, -- cursor in an unfocused terminal
     ErrorMsg        = { fg = spec.diag.error }, -- error messages on the command line
     VertSplit       = { fg = c.border.default }, -- the column separating vertically split windows
+    WinSeparator    = { fg = c.border.default }, -- (nvim >= 0.10) the column separating vertically split windows
     Folded          = { fg = spec.fg3, bg = spec.bg2 }, -- line used for closed folds
     FoldColumn      = { fg = spec.fg3 }, -- 'foldcolumn'
     SignColumn      = { fg = spec.fg3 }, -- column where |signs| are displayed