fix(deps): upgrade execa to v8

[mrstork]

Summary

Now that we've dropped support for v14 and v16 we are able to leverage the next major version of execa
Unfortunately v9 requires node 18.19 or higher, so we cannot move up to the latest version quite yet

Fixes FRB-1779

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[43081j]

FYI you may be able to move to tinyexec which will get you a whole bunch of savings

it should work fine on 18.*