XMLTV 4.0.0

Breaking

• Removed support for PHP 7.2, 7.3, 7.4
• Removed deprecated XmlElement::withOptionalChild() method (156c077)
• Specification xmltv.dtd was moved to src-folder (9007819)

Changes

• Improved typing (d097b24)

Fixes

• Fixed issues found by Psalm and Phan (8ce7e4d)