Actions - octokit.yml - Ubuntu, macOS, & Windows - Ruby 2.5 thru master

[MSP-Greg]

Two Commits:

1. 'Actions - octokit.yml - run Ubuntu, macOS, & Windows - Ruby 2.5 thru master'

2. 'Gemfile - add rexml & rss for Ruby master' - rexml & rss are no longer default gems

[MSP-Greg]

Updated for changes in Actions, etc.

Renamed workflow file to octokit.yml, helpful when one has more than one workflow in their editor.

[MSP-Greg]

@hmharvey

Thank you. I added '*' to push branches. This is needed if contributors want to run CI in their fork easily. But, I think it causes CI to run twice when maintainers/owners work with a branch here for a PR. I'm pretty sure I opened an issue in actions/runner. I think.

on:
   push:
     branches:
     - master
     - 4-stable
     - '*'