0.6.0

What's Changed

• remove Step.closeout by @braingram in #152
• align style checks with other spacetelescope repos by @braingram in #157
• install numpy<2 in oldestdeps by @braingram in #158
• switch to sphinx_rtd_theme by @braingram in #159
• Remove unused code to simplify filename generation by @braingram in #154

Full Changelog: 0.5.2...0.6.0