heyoka 0.9.0

[bluescarni]

This release includes two new functions in the expression system: the inverse of Kepler's elliptic equation and time polynomials.

Additionally, this release features also performance improvements and various internal cleanups.

The full changelog, as usual, is available here:

https://bluescarni.github.io/heyoka/changelog.html

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This discussion was created from the release heyoka 0.9.0.