floss: Uprev bitflags package to 2.4.0

The old bitflags version causes "error: &-masking with zero" error when
running clippy.

Bug: 343315863
Tag: #floss
Test: mmm packages/modules/Bluetooth
Test: ./build.py --target clippy, topshim passed
Test: ./build.py --target test
Test: Deploy to Guybrush, tested PhoneHub/SmartLock/FastPair/NearbyShare
Test: AVL test together with https://r.android.com/3119556
Flag: EXEMPT, Floss-only changes
Change-Id: I63f5cb3e11208fc609dcce0d4df015e58efc7f2a