Fix int parsing

[Licenser]

We falsly returned i64 for non negative numbers that were in the i64 range; fixes #383

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Benchmark for f37ae68

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Test	Base	PR	%
apache_builds/simd_json::to_tape_with_buffers	91.2±4.10µs	90.9±1.33µs	-0.33%
canada/simd_json::to_tape_with_buffers	3.7±0.16ms	3.7±0.14ms	0.00%
citm_catalog/simd_json::to_tape_with_buffers	1134.1±81.65µs	1132.6±74.85µs	-0.13%
event_stacktrace_10kb/simd_json::to_tape_with_buffers	3.7±0.20µs	3.7±0.21µs	0.00%
github_events/simd_json::to_tape_with_buffers	39.8±0.95µs	39.9±0.93µs	+0.25%
log/simd_json::to_tape_with_buffers	1517.7±70.16ns	1578.7±73.38ns	+4.02%
twitter/simd_json::to_tape_with_buffers	438.9±26.57µs	437.0±25.58µs	-0.43%

[github-actions]

Benchmark for f08d03a

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Test	Base	PR	%
apache_builds/simd_json::to_tape_with_buffers	93.0±3.45µs	91.5±2.26µs	-1.61%
canada/simd_json::to_tape_with_buffers	3.8±0.17ms	3.7±0.15ms	-2.63%
citm_catalog/simd_json::to_tape_with_buffers	1135.5±83.09µs	1131.0±81.96µs	-0.40%
event_stacktrace_10kb/simd_json::to_tape_with_buffers	3.8±0.25µs	3.8±0.26µs	0.00%
github_events/simd_json::to_tape_with_buffers	40.2±1.26µs	40.7±1.28µs	+1.24%
log/simd_json::to_tape_with_buffers	1548.3±76.62ns	1606.7±105.92ns	+3.77%
twitter/simd_json::to_tape_with_buffers	446.1±28.89µs	445.3±29.43µs	-0.18%

[github-actions]

Benchmark for a009936

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Test	Base	PR	%
apache_builds/simd_json::to_tape_with_buffers	92.4±2.35µs	91.7±1.55µs	-0.76%
canada/simd_json::to_tape_with_buffers	3.8±0.16ms	3.9±0.13ms	+2.63%
citm_catalog/simd_json::to_tape_with_buffers	1143.3±89.75µs	1133.9±83.52µs	-0.82%
event_stacktrace_10kb/simd_json::to_tape_with_buffers	3.9±0.31µs	3.8±0.31µs	-2.56%
github_events/simd_json::to_tape_with_buffers	41.5±1.38µs	40.7±1.21µs	-1.93%
log/simd_json::to_tape_with_buffers	1589.2±100.97ns	1585.8±97.85ns	-0.21%
twitter/simd_json::to_tape_with_buffers	444.8±31.06µs	444.9±27.18µs	+0.02%