use capture3 instead of popen3

Author: ianfixes

lib/arduino_ci/host.rb

@@ -48,11 +48,10 @@ def self.symlink(old_path, new_path)
       # windows mklink syntax is reverse of unix ln -s
       # windows mklink is built into cmd.exe
       # vulnerable to command injection, but okay because this is a hack to make a cli tool work.
-      _stdin, stdout, stderr, wait_thr = Open3.popen3('cmd.exe', "/c mklink /D #{new_path} #{old_path}")
-      wait_exit = wait_thr.value
+      stdout, stderr, exitstatus = Open3.capture3('cmd.exe', "/c mklink /D #{new_path} #{old_path}")
       STDERR.puts stdout
       STDERR.puts stderr
-      wait_exit.exitstatus
+      exitstatus
     end
   end
 end