Self-test failure on 32-bit i386 architecture

[jas4711]

Hi. I'm packaging this for Debian, and we noticed a self-check failure when building for 32-bit architectures.

=== RUN   TestParseAttributeCerts
    attributecert_test.go:79: failed to parse test data testdata/plat_cert1.cer: asn1: structure error: integer too large
--- FAIL: TestParseAttributeCerts (0.01s)

https://salsa.debian.org/jas/golang-github-google-go-attestation/-/jobs/8165420

Thanks,
Simon