libavif v1.0.3 release

[Wan-Teh Chang]

Hello everyone,

libavif v1.0.3 has been released to fix a critical bug. The
source code of the release can be checked out from the git
repository[1] using the release tag v1.0.3.

[1] https://github.com/AOMediaCodec/libavif.git

Here is the change log:

[1.0.3] - 2023-12-03

Changed
* Rewrite the fix for memory errors reported in crbug.com/1501770.
* Fix memory errors reported in crbug.com/1504792 by [Fudan
University](https://secsys.fudan.edu.cn/).
* src/reformat.c: Allocate the threadData array directly.