Adds official support for PHP 8.2.

Scrutinizer and core dependency updates.

Adds support for PHP 8.1

Adds support for PHP 8.0. PHPUnit also updated to v9.

Adding build/testing against PHP 7.4. and bumped dependencies.

Minor release (updating composer dependency versions)

Implements some additional checks and handles GPIO file updates more efficiently. This release resolves issues where an "I/O error" is is intermittently shown when using the library as the library now gracefully handles GPIO file update errors and works around these problems.

Minor tweaks to the travis PHP build targets (now tests against PHP 7.3 too).

Adds inverted logic handling.