Nested-Pandas v0.4.4

What's Changed

• Fix .nest.to_flatten_inner for empty inputs by @hombit in #267
• Implement delitem for NestedFrame by @hombit in #269
• Propagate inner nested columns to elements by @hombit in #271
• Fix to_flatten_inner for repeated index by @hombit in #272
• Pandas 2.3 by @hombit in #279
• Drop Python 3.9, bump PPT by @hombit in #280

Full Changelog: v0.4.3...v0.4.4