FAB should have a shadow at elevation level 3

### Current behaviour
When in M3, the shadow of the FAB is at level 6.

### Expected behaviour
According to [M3 spec](https://m3.material.io/components/floating-action-button/specs), the FAB should have a shadow of level 3. I reported this for the AnimatedFAB back in #3805 and it seems to only have been fixed for the Animated version.

### Your Environment

| software | version
| --------------------- | -------
| react-native | 0.71.8
| react-native-paper | 0.5.8

The issue names the FAB, the AnimatedFAB issue #3805, and the M3 specification; it does not identify a file or test. Start by locating the FAB elevation implementation and comparing it with the AnimatedFAB fix, then verify that the M3 FAB shadow is level 3 according to the linked specification.

Written by the indexing model from the issue text.