Avoid WSL bug in file watching in dotnet runtime

Newer roslyn versions run into stack overflow errors when initializing.
It seems to only happen on WSL and it is related to running roslyn as a
systemd service.

<seblyng/roslyn.nvim#303 (comment)>

Author: NonlinearFruit

nvim/lua/plugins/csharp.lua

@@ -40,7 +40,8 @@ end
 
 local function install_lsp_and_dap_if_needed()
   require("installer").install_if_missing({
-    -- "roslyn", -- LSP Needs to be manually installed from the Mason gui?
+    -- Avoid WSL bug in file watching in dotnet runtime <https://github.com/seblyng/roslyn.nvim/issues/303#issuecomment-4144530656>
+    "roslyn@5.4.0-2.26175.10", -- LSP Needs to be manually installed from the Mason gui?
     "netcoredbg", -- DAP
   })
 end