Log Message:
protobuf py-protobuf: updated to (5.)28.3

Protocol Buffers v28.3

C++

Fix packed reflection handling bug in edition 2023.

Java

Mute the minor version warning
Populate Kotlin Manifest Files
Re-export includingDefaultValueFields in deprecated state for important Cloud \ 
customer. (3b62d78)
Cherrypick restoration of mutableCopy helpers (3ea568a)
Fix packed reflection handling bug in edition 2023.

Kotlin

Populate Kotlin Manifest Files

Python

Mute the minor version warning
Fix packed reflection handling bug in edition 2023.

Other

Fix merge conflicts (664a7e1)
[ObjC] Disabling visionOS on CI. (22cd8ba)
Update staleness tests to only run over release branch