Add missing / in URI::Source#to_s

Co-authored-by: Vinicius Stock <[email protected]>

Author: amomchilov

lib/ruby_lsp/requests/support/source_uri.rb

@@ -66,7 +66,7 @@ def check_host(v)
 
     #: -> String
     def to_s
-      "source://#{gem_name}/#{gem_version}#{path}##{line_number}"
+      "source://#{gem_name}/#{gem_version}/#{path}##{line_number}"
     end
 
     if URI.respond_to?(:register_scheme)