Remove .pp from Ruby extension list. Issue #5366

[dhollinger]

The *.pp file extension as it pertains it Ruby is actually
a file type used to denote a Puppet Manifest written in the Puppet
DSL (which itself is written in Ruby). The affected setting was
overriding VSCode Puppet extensions that are expecting the .pp
extension to be detected as file type Puppet.

[mention-bot]

By analyzing the blame information on this pull request, we identified @Ikuyadeu and @egamma to be potential reviewers

[msftclas]

Hi @dhollinger, I'm your friendly neighborhood Microsoft Pull Request Bot (You can call me MSBOT). Thanks for your contribution!

This seems like a small (but important) contribution, so no Contribution License Agreement is required at this point. Real humans will now evaluate your PR.

TTYL, MSBOT;

[aeschli]

Thanks @dhollinger !