fix: build script for Non-English environment

[Dreagonmon]

Questions

• Did you test your changes or double-check that they work?
• Did you read and follow the Atlas Contribution Guidelines?

Describe your pull request

fix build script for Non-English environment.

I want to test my modified version of playbook, but the output of the test target seems having a broken xml format.

It turns out that I use the Chinese environment and powershell use the Chinese encoding to read and write playbook.conf file, that would break the Description content which contains special characters.

So here is the fix, simply add -Encoding to the read and write commands.