Release 0.4.0

What's Changed

• Type hierarchy 2 by @marcofavorito in #75
• Fix/type hierarchy by @francescofuggitti in #73
• Override equal for derived predicates by @francescofuggitti in #74
• Make pickling to work on domains/problems objects (Fix #79) by @marcofavorito in #80
• Update dependencies by @marcofavorito in #81
• Fixes and improvements in the parsing of typed lists by @marcofavorito in #82
• Fix printing of empty Ands and Ors by @francescofuggitti in #83
• Issue 87 by @francescofuggitti in #90
• Support for numeric fluents and action costs by @francescofuggitti in #92
• build(deps-dev): bump certifi from 2023.5.7 to 2023.7.22 by @dependabot in #85

Full Changelog: v0.3.1...v0.4.0