message: Remove quotes from README
diff: This action sets up a php environment along with composer on multiple platforms for use in github actions.
  # PHP Version Support
  -- '5.6'
  -- '7.0'
  -- '7.1'
  -- '7.2'
  -- '7.3'
  +- 5.6
  +- 7.0
  +- 7.1
  +- 7.2
  +- 7.3
  # Operating Systems Support
  - Linux (ubuntu-latest)
  