Plotly

Added
- Add `griddash` axis property to cartesian, polar, smith, ternary and geo subplots and add `griddash` and `minorgriddash` to `carpet` trace [[6144](https://github.com/plotly/plotly.js/pull/6144)], with thanks to njwhite for the contribution!
- Implement various options to position and style `minor` ticks and grid lines on cartesian axis types including
`minor.tickmode`, `minor.tickvals`, `minor.tickcolor`, `minor.ticklen`, `minor.tickwidth`, `minor.dtick`, `minor.tick0`, `minor.nticks`, `minor.ticks`,
`minor.showgrid`, `minor.gridcolor`, `minor.griddash` and `minor.gridwidth` [[6166](https://github.com/plotly/plotly.js/pull/6166)]

Changed
- Use the "willReadFrequently" 2d context creation attribute to optimize readback performance [[6084](https://github.com/plotly/plotly.js/pull/6084)],
with thanks to junov for the contribution!

Fixed
- avoid drawing blank tick labels on cartesian axes [[6163](https://github.com/plotly/plotly.js/pull/6163)]

Fixed
- Regenerate functions of regl-based traces in the "strict" bundle [[6141](https://github.com/plotly/plotly.js/pull/6141)]

Added
- Add a CSP complaint variation of regl-based traces i.e. `parcoords`, `splom`, `scattergl`, `scatterpolargl` to the "strict" bundle [[6083](https://github.com/plotly/plotly.js/pull/6083)]
- Add `scattersmith` trace to the "strict" bundle [[6135](https://github.com/plotly/plotly.js/pull/6135)]

Fixed
- Fix `mesh3d` generation when `alphahull` is a positive number (regression introduced in 2.5.1) [[6133](https://github.com/plotly/plotly.js/pull/6133)]

Added
- Add support to use version 3 of MathJax and add `typesetMath` attribute to config [[6073](https://github.com/plotly/plotly.js/pull/6073)],
with thanks to [Equinor](https://www.equinor.com) for sponsoring the related development!
- Add `fillpattern` options to `scatter` trace [[6101](https://github.com/plotly/plotly.js/pull/6101)],
with thanks to s417-lama for the contribution!

Added
- Implement `ticklabelstep` to reduce labels on 2D axes and colorbars [[6088](https://github.com/plotly/plotly.js/pull/6088)],
this feature was anonymously sponsored: thank you to our sponsor!

Changed
- Display the version of plotly.js when hovering over the modebar [[6077](https://github.com/plotly/plotly.js/pull/6077)]
- Various dependency updates as listed under [the v2.9.0 milestone](https://github.com/plotly/plotly.js/milestone/69?closed=1)

Fixed
- Fix vertical spacing of legend items in horizontal mode [[6094](https://github.com/plotly/plotly.js/pull/6094)]