PHP 8 support

• Add support for PHP 8

Thanks @pascalbaljet !

1.6.0

• Drop support for PHP 5.x.
• Set minimum requirement of PHP 7.2.
• Update dependencies.

Thanks @ADmad!

1.5.0

• Added focal point zooming. Thanks Jason!
• Fixed an issue with deleting temp files. Thanks Barry!
• Dropped support for PHP 5.4.

1.4.0

• Add WebP support. Thanks James!

1.3.0

• Added new flip manipulation. Thanks James!

1.2.2

• Fix issue with progressive JPEGs being saved as ".pjpg" when using extensions on cache filenames. Thanks Jason!

1.2.1

• Fix issue where the source filename was being trimmed when it begins with the base URL. Thanks Jason!

1.2.0

• Add ability to set the opacity of a watermark. Thanks Marek!

1.1.1

• Fix bug with progressive jpeg encoding.

1.1.0

• Add support for caching with file extensions. Thanks Jason!