Roll Flutter Engine from 23763db72272 to 20742e37e54e (1 revision) (#142850)

https://github.com/flutter/engine/compare/23763db72272...20742e37e54e

2024-02-03 jonahwilliams@google.com [Impeller] fix flake in compute unittests. (flutter/engine#50308)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC matanl@google.com,rmistry@google.com,zra@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

bin/internal/engine.version

-23763db7227244cc5e443a0b49a1432b01b99fd0
+20742e37e54ed908654b17ff70d894a1d844daab