Fixed UnionAll deprecation warning

[miguelmaso]

• Fixed deprecation warning
• Thanks to the fix, all the length are equal at compile time -> the check is not needed anymore

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	cbc3d50...	main / cbc3d50...
Constitutive models/Visco-elastic Ψ	0.0471 ± 0.034 ms	0.0475 ± 0.034 ms	0.992 ± 1
Constitutive models/Visco-elastic ∂Ψu	0.0531 ± 0.0016 ms	0.0536 ± 0.0017 ms	0.991 ± 0.044
Constitutive models/Visco-elastic ∂Ψuu	0.1 ± 0.012 ms	0.101 ± 0.012 ms	0.995 ± 0.17
Simulations/StaticMechanicalDirichlet	0.133 ± 0.0063 s	0.133 ± 0.0062 s	0.996 ± 0.066
Simulations/StaticMechanicalNeumann	0.127 ± 0.01 s	0.127 ± 0.011 s	0.999 ± 0.12
Simulations/ViscoElastic	18.1 s	18.1 s	0.996
Tensor algebra/Cofactor	0.07 ± 0.01 μs	0.061 ± 0.01 μs	1.15 ± 0.25
Tensor algebra/Det(A)Inv(A')	0.13 ± 0.001 μs	0.13 ± 0.01 μs	1 ± 0.077
Tensor algebra/δδ_λ_2d	30 ± 0 ns	30 ± 0 ns	1 ± 0
Tensor algebra/δδ_μ_2d	30 ± 0 ns	30 ± 0 ns	1 ± 0
time_to_load	2.61 ± 0.019 s	2.6 ± 0.0094 s	1 ± 0.008

Memory benchmarks

	main	cbc3d50...	main / cbc3d50...
Constitutive models/Visco-elastic Ψ	1.24 k allocs: 0.0777 MB	1.24 k allocs: 0.0777 MB	1
Constitutive models/Visco-elastic ∂Ψu	1.29 k allocs: 0.0826 MB	1.29 k allocs: 0.0826 MB	1
Constitutive models/Visco-elastic ∂Ψuu	2.25 k allocs: 0.149 MB	2.25 k allocs: 0.149 MB	1
Simulations/StaticMechanicalDirichlet	1.51 M allocs: 0.109 GB	1.51 M allocs: 0.109 GB	1
Simulations/StaticMechanicalNeumann	1.48 M allocs: 0.0933 GB	1.48 M allocs: 0.0933 GB	1
Simulations/ViscoElastic	0.326 G allocs: 20.5 GB	0.326 G allocs: 20.5 GB	1
Tensor algebra/Cofactor	1 allocs: 0.0781 kB	1 allocs: 0.0781 kB	1
Tensor algebra/Det(A)Inv(A')	4 allocs: 0.25 kB	4 allocs: 0.25 kB	1
Tensor algebra/δδ_λ_2d	0 allocs: 0 B	0 allocs: 0 B
Tensor algebra/δδ_μ_2d	0 allocs: 0 B	0 allocs: 0 B
time_to_load	0.149 k allocs: 11.1 kB	0.149 k allocs: 11.1 kB	1