Add Julia 1.13 to CI test matrix

[vchuravy]

Co-Authored-By: Claude Sonnet 4.6 noreply@anthropic.com

[github-actions]

Benchmark Results

	main	27c8321...	main / 27c8321...
basics/make_zero/namedtuple	0.0519 ± 0.0032 μs	0.0527 ± 0.0038 μs	0.984 ± 0.094
basics/make_zero/struct	0.273 ± 0.0086 μs	0.274 ± 0.0055 μs	0.995 ± 0.037
basics/overhead	5.25 ± 0.01 ns	5.26 ± 0.01 ns	0.998 ± 0.0027
basics/remake_zero!/namedtuple	0.227 ± 0.0094 μs	0.224 ± 0.0073 μs	1.02 ± 0.053
basics/remake_zero!/struct	0.228 ± 0.013 μs	0.226 ± 0.009 μs	1.01 ± 0.068
fold_broadcast/multidim_sum_bcast/1D	10.2 ± 0.21 μs	10.2 ± 0.27 μs	1 ± 0.034
fold_broadcast/multidim_sum_bcast/2D	12.1 ± 0.29 μs	12.1 ± 0.22 μs	1 ± 0.03
time_to_load	1.03 ± 0.0097 s	1.04 ± 0.014 s	0.987 ± 0.016

Benchmark Plots

A plot of the benchmark results has been uploaded as an artifact at https://github.com/EnzymeAD/Enzyme.jl/actions/runs/25914412858/artifacts/7015798178.