fix: missing . in temp file which leads creating extensionless file

Author: tomocrafter

lib/execjs/external_runtime.rb

@@ -59,7 +59,7 @@ def create_tempfile(basename)
         end
 
         def write_to_tempfile(contents)
-          tmpfile = create_tempfile(['execjs', 'js'])
+          tmpfile = create_tempfile(['execjs', '.js'])
           tmpfile.write(contents)
           tmpfile.close
           tmpfile