sumneko-lua-language-server: 2.6.7 -> 2.6.8

[lockejan]

Description of changes

Version bump.

Release notes:
2.6.8 https://github.com/sumneko/lua-language-server/releases/tag/2.6.8

I compiled and tested basic functionality within neovim under x86_64-darwin

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.05 Release Notes (or backporting 21.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[lockejan]

since version 3.0.0 and 3.0.1 seems to introduce some issues and breaking changes, this PR now only targets the next minor version bump instead.

[lockejan]

Result of nixpkgs-review pr 168058 run on x86_64-darwin 1

1 package built:

• sumneko-lua-language-server

[lockejan]

Deprecated by #168929