Update file(s) from wp-cli/.github

Merge pull request #44 from wp-cli/regenerate-readme

Merge pull request #42 from wp-cli/update-wp-cli-tests-v4

Removed psr autoloader because "src" folder doesn't exist (#41)

This fixes the issue described here: wp-cli/wp-cli#5731

Update file(s) from wp-cli/.github

Merge pull request #18 from kingkero/windows-combability

change to switch, add option for windows systems