Numba: faster Alloc implementation

[ricardoV94]

Before

Name (time in us)                           Min                Mean             StdDev              Median            Rounds
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test_alloc_benchmark_numba[scalar]      63.7000 (1.0)       67.3365 (1.0)       9.5839 (1.0)       64.8110 (1.0)       15791
test_alloc_benchmark_numba[outer]      215.2940 (3.38)     223.2032 (3.31)     18.6194 (1.94)     219.6620 (3.39)       4749
test_alloc_benchmark_numba[inner]      216.2260 (3.39)     232.2599 (3.45)     52.9809 (5.53)     224.9920 (3.47)       4661

After

Name (time in us)                          Min               Mean             StdDev             Median            Rounds
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test_alloc_benchmark_numba[scalar]     65.2430 (1.0)      72.5559 (1.0)      24.4287 (1.34)     67.7070 (1.0)       15234
test_alloc_benchmark_numba[inner]      66.8160 (1.02)     77.5265 (1.07)     26.5970 (1.45)     70.6130 (1.04)      15218
test_alloc_benchmark_numba[outer]      71.5940 (1.10)     82.2667 (1.13)     18.2818 (1.0)      77.2250 (1.14)      13920
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