Ensure sorbet-runtime available for runner

Author: andyw8

lib/ruby_lsp/ruby_lsp_rails/runner_client.rb

@@ -48,7 +48,14 @@ def initialize
           # If we can't set the session ID, continue
         end
 
-        stdin, stdout, stderr, wait_thread = Open3.popen3(
+        env = {}
+        if File.exist?(bundle_gemfile = ::Rails.root.join(".ruby-lsp/Gemfile"))
+          env = { "BUNDLE_GEMFILE" => bundle_gemfile }
+        end
+
+        # TODO: fix signature
+        stdin, stdout, stderr, wait_thread = T.unsafe(Open3).popen3(
+          env,
           "bin/rails",
           "runner",
           "#{__dir__}/server.rb",