Can't use splat to expand arguments in `@variable`

[stillyslalom]

From Discourse,

julia> ε = @variables ε_xx, ε_yy, ε_xy
3-element Vector{Num}:
 ε_xx
 ε_yy
 ε_xy

julia> @variables η(ε...) # can't use splat to expand
ERROR: MethodError: no method matching value(::Num, ::Num, ::Num)
Closest candidates are:
  value(::Num) at C:\Users\alexa\.julia\packages\Symbolics\mFWWM\src\num.jl:19
  value(::Any) at C:\Users\alexa\.julia\packages\Symbolics\mFWWM\src\num.jl:18
Stacktrace:
 [1] top-level scope
   @ REPL[24]:1

julia> @variables η(ε[1], ε[2], ε[3]) # have to manually expand
1-element Vector{Num}:
 η(ε_xx, ε_yy, ε_xy)

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