v0.40 Changelog (#6760)

This PR will be a landing page for other PRs for individual changelog
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Co-authored-by: Mudit Pandey <[email protected]>
Co-authored-by: ANTH0NY <[email protected]>
Co-authored-by: Austin Huang <[email protected]>
Co-authored-by: AntonNI8 <[email protected]>
Co-authored-by: Diego <[email protected]>
Co-authored-by: Diego <[email protected]>
Co-authored-by: Jay Soni <[email protected]>
Co-authored-by: qottmann <[email protected]>
Co-authored-by: Josh Izaac <[email protected]>