WGLMakie example uses deprecated arg + unclear requirements and compat for examples

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The WGLMakie example uses rotations which has been deprecated in Makie 0.21

Bonito.jl/examples/wglmakie.jl

Line 29 in 1a6083e

scatter(1:4, marker='▲', markersize=0.3, markerspace=:data, rotations=LinRange(0, pi, 4)),

In addition, it's not completely clear what the requirements are for the examples and which versions. For example it could have a Makie 0.20 compat in which case the above would not be a problem. Should the examples folder have an associated Project.toml?