Change get_tournament_selection_weights function signature (#395)

* Change `get_tournament_selection_weights` options type to AbstractOptions

`get_tournament_selection_weights`, presently, only accepts `options::Options`. This created a bottleneck for LaSR (or any other SymbolicRegression.jl customization) that relies on multiple dispatch of subtypes of `AbstractOptions` type. Changing the function signature doesn't impact the test cases in SymbolicRegression.jl.

* refactor: improve type instability in `get_tournament_selection_weights`

---------

Co-authored-by: Miles Cranmer <miles.cranmer@gmail.com>

src/Population.jl

@@ -167,9 +167,9 @@ const CACHED_WEIGHTS =
         PerThreadCache{Dict{Tuple{Int,Float32},typeof(test_weights)}}()
     end
 
-@unstable function get_tournament_selection_weights(@nospecialize(options::Options))
-    n = options.tournament_selection_n
-    p = options.tournament_selection_p
+@unstable function get_tournament_selection_weights(@nospecialize(options::AbstractOptions))
+    n = options.tournament_selection_n::Int
+    p = options.tournament_selection_p::Float32
     # Computing the weights for the tournament becomes quite expensive,
     return get!(CACHED_WEIGHTS, (n, p)) do
         k = collect(0:(n - 1))