use === instead of == to compare Symbols

[ranocha]

I found invalidations from loading both RecipesBase.jl and SciMLBase.jl using the beta of Julia 1.9:

julia> using Pkg; Pkg.activate(temp=true); Pkg.add("SciMLBase"); Pkg.develop("RecipesBase")

julia> using SnoopCompileCore; invalidations = @snoopr(using RecipesBase, SciMLBase); using SnoopCompile

julia> trees = invalidation_trees(invalidations)
[...]
 inserting ==(retcode::SciMLBase.ReturnCode.T, s::Symbol) @ SciMLBase ~/.julia/packages/SciMLBase/QqtZA/src/retcodes.jl:348 invalidated:
   backedges: 1: superseding ==(x, y) @ Base Base.jl:127 with MethodInstance for ==(::Any, ::Symbol) (12 children)

I fixed invalidations by using === instead of == when comparing to a Symbol, which is also recommended in the docstring of Symbol:

help?> Symbol
search: Symbol
[...]
  Symbols are immutable and should be compared using ===. The implementation re-uses the same object for all
  Symbols with the same name, so comparison tends to be efficient (it can just compare pointers).
[...]

[ranocha]

CI fails with a lot of Path to conda environment is not valid errors that do not seem to be related to this PR?

[BeastyBlacksmith]

Thanks!