v0.1.6

• This minor update was necessary to maintain compatibility with the latest versions of 'dplyr'.
• Increment supported version of R from R (>= 3.5.0) to R (>= 3.6.0)
• Also minor tooling changes to add pre-commit and 'renv' and remove AppVeyor and Travis CI (only using GitHub Actions, now).
• Add code coverage report CI as a GitHub Action (based on implementation by 'ggplot2')