Release v0.3.0-alpha.1

After a successful launch a couple of weeks ago, we're back with our first release!
With a few exceptions this release focuses on internal refactors & improving our processes.
However, we think you'll enjoy these goodies that made it in nonetheless!

https://user-images.githubusercontent.com/2910679/222510504-23871b8c-0bef-49c2-bbd2-37baab4247e8.mp4

* You can now generate point clouds directly from depth textures! Check out @teh-cmc's [video](https://www.youtube.com/watch?v=7eJWS_DGBn0) on how to use it.
  * This is **a lot** faster and more convenient than doing so manually in your own code
  * Allows to choose you from a wide variety of color maps
  * Picking is not yet working
* Python packages now work with Ubuntu-20.04 [#1334](https://github.com/rerun-io/rerun/pull/1334)
* Improve display of date-times in plots [#1356](https://github.com/rerun-io/rerun/pull/1356)
* UI scale factor is saved across sessions and more persistent between screens [#1448](https://github.com/rerun-io/rerun/pull/1448)
* SDK:
  * 2D Line strips can now be logged directly [#1430](https://github.com/rerun-io/rerun/pull/1430)
  * Add a `strict` mode to the Python SDK where misuses of the API results in exceptions being raised.[#1477](https://github.com/rerun-io/rerun/pull/1477)
* Showing tensors in the viewer is now faster
* Log streams / .rrd files are now versioned [#1420](https://github.com/rerun-io/rerun/pull/1420)
    * ⚠️ BREAKING: old `.rrd` files no longer load
* Less build dependencies ([still more work to do!](https://github.com/rerun-io/rerun/issues/1316))
  * notably, we previously used a version of the `time` crate which had a security issue (CVE-2020-26235)
* Print more information & troubleshooting info on crash
* u8 segmentation stay u8 now (they converted to u16 before) [#1376](https://github.com/rerun-io/rerun/pull/1376)