Release 0.20.3

[eddelbuettel]

This PR updates the package to release 0.20.3. From NEWS.md (with 'lowered' headline levels for display here):

tiledb 0.20.3

• This release of the R package builds against TileDB 2.16.2, and has also been tested against earlier releases as well as the development version (Release 0.20.3 #582)

Improvements

• Use of TileDB Embedded was upgraded to release 2.16.2 (Use TileDB 2.16.2 #581)

[shortcut-integration]

This pull request has been linked to Shortcut Story #32383: Improve label_index documentation.

[eddelbuettel]

GH tricked me. I commited the change to DESCRIPTION the usual way, then the pkgdown update under [ci skip] and net-net both were skipped.

But there is no code here, and we just passed for 2.16.2 so we should be fine.