CompatHelper: bump compat for UnicodePlots to 3 for package test, (keep existing compat) (#83)

Co-authored-by: CompatHelper Julia <compathelper_noreply@julialang.org>
Co-authored-by: Hendrik Ranocha <ranocha@users.noreply.github.com>

Author: 3 people

test/Project.toml

@@ -9,4 +9,4 @@ UnicodePlots = "b8865327-cd53-5732-bb35-84acbb429228"
 Aqua = "0.5"
 Plots = "1"
 StaticArrays = "1.3"
-UnicodePlots = "2"
+UnicodePlots = "2, 3"