Prevent workspace dependencies from failing if there's no bundle (#3655)

### Motivation

The `workspace_dependencies` custom request may fail if there's no Gemfile. We need to handle that possibility.

### Implementation

All we have to do is rescue the error raised by Bundler when there's no Gemfile.

Author: vinistock

lib/ruby_lsp/server.rb

@@ -1224,7 +1224,7 @@ def workspace_dependencies(message)
             }
           end
         end
-      rescue Bundler::GemNotFound
+      rescue Bundler::GemNotFound, Bundler::GemfileNotFound
         []
       end