Added GITHUB_TOKEN explicitly to risczero install

[mothran]

Attempt to fix 403 errors in the CI by manually setting the GITHUB_TOKEN during the risczero install command:

Reference error in CI: https://github.com/risc0/risc0/actions/runs/5826106139/job/15799276430?pr=759#step:6:951

[github-actions]

Benchmark for Linux-cuda

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Benchmark for Linux-default

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Benchmark for macOS-default b704531

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Test	Base	PR	%
fib/100/execute	2.8±0.13ms	2.7±0.13ms	-3.57%
fib/100/prove	3.7±0.08s	3.6±0.07s	-2.70%
fib/100/total	3.7±0.05s	3.7±0.07s	0.00%
fib/1000/execute	3.0±0.07ms	2.9±0.14ms	-3.33%
fib/1000/prove	3.7±0.06s	3.7±0.07s	0.00%
fib/1000/total	3.7±0.06s	3.7±0.05s	0.00%
fib/10000/execute	5.2±0.06ms	5.0±0.11ms	-3.85%
fib/10000/prove	15.3±0.10s	15.2±0.11s	-0.65%
fib/10000/total	15.3±0.11s	15.3±0.10s	0.00%

Benchmark for macOS-metal

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[flaub]

Nice, thanks for this