fix 2d examples not compiling

[spookyvision]

Objective

• fix 2d examples not compiling, error was:

$ cargo run --example $ANY_AVIAN2D_EXAMPLE
error[E0433]: failed to resolve: use of undeclared type `Animatable`
   --> crates/avian2d/../../src/diagnostics/ui.rs:434:24
    |
434 |         text_color.0 = Animatable::interpolate(&green, &red, t.min(1.0)).into();
    |                        ^^^^^^^^^^ use of undeclared type `Animatable`

Solution

• add bevy_animation to bevy feature flags in examples_common_2d