chore: bump version

feat: ensure passed tags are strings

Newer versions of PHP raise a warning if you attempt to use array syntax
against non-strings / non-arrays. Added sanity check to ensure we're
working with a string, otherwise skip it.

Also added in PHP 8.1 to the testing suite and bumped the copyright.

Bumped version to 2.0 since as the change in expected output is a
breaking change.

ci: switch to github actions

Dropped Travis CI and Coveralls for GitHub Actions and CodeCov.

chore(ci): test against PHP 7.4

* Updated to test again PHP 7.4 and to use that for coverage reporting.
* Added PHP nightly builds as an allowable failure.
* Added a git ignore as well as a `phpunit` configuration.
* Updated the tests and CI configuration to better handle the juggling of PHP and `phpunit` versions.
* Updated the coveralls dependency to be the latest and greatest instead of the deprecated package.
* Tweaked the README, updated the LICENSE years and bumped this package's version.
* Dropped Patreon link in favor of using Github Sponsors.

PHP 7.3 and more

* Added CI for PHP 7.3
* Dropped CI for HHVM (was running into too many issues out of no where)
* Reworked CI distros where I could
* Bumped copyright year
* Cleaned up the README, fixed spacing, dumped some of the wordiness

Merge pull request #1 from joshtronic/development

Vocab tweaks, 7.2 and HHVM testing, cleanup

Bump version number

Updated badges

Dropped require from README

Kind of obvious you need to require the library. If using composer, the
autoloader will take care of it.