PR from Andrew Hayworth

While fixing the gem build, I noticed that the gem will not run on arm64 machines, like the new spiffy M1/M2 MacBooks. On a whim, I tried just removing that restriction... and it does seem to work:

foundationdb/bindings/ruby/lib on  ahayworth/fix-ruby-binding-build [?] via 💎 v3.2.1 took 2s
zsh ❯ pry
[1] pry(main)> require 'fdb'
=> true
[2] pry(main)> FDB.api_version 720
LoadError: FoundationDB API only supported on x86_64 (not arm64)
from /Users/andrew/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/fdb-7.3.0/lib/fdbimpl.rb:40:in `<module:FDBC>'
[3] pry(main)>

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