fix: use EAFP try/except for os.getegid/geteuid in stat() (issue #177)

[Quantum0uasar]

Replace LBYL platform check with EAFP try/except AttributeError pattern.

os.getegid() and os.geteuid() are unavailable on Windows and other non-POSIX platforms (e.g. WASI), raising AttributeError. Rather than checking the platform up front, wrap the assignments in a try/except block so group_access and user_access are simply omitted when the underlying OS calls are not available.

Closes #177

[linux-foundation-easycla]

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[Quantum0uasar]

@slott56 Hi! Would you be able to take a look when you get a chance? All CI checks are passing — just needs a review to merge. Happy to make any changes if needed.

[kapilt]

@Quantum0uasar are you able to do the cncf cla per other pr comment? Direct link https://api.easycla.lfx.linuxfoundation.org/v2/repository-provider/github/sign/14202841/272774581/179/#/?version=2

[Quantum0uasar]

Good catch on the EAFP refactor — the try/except AttributeError approach is definitely the right call here over platform string checking. A couple of notes:

1. The data dict used inside the try block — make sure it's initialized before this block so the except: pass path still returns a valid (partial) map without the access keys. Looks correct from the diff but worth confirming in context.
2. It might be worth a brief comment above the try block explaining why AttributeError is caught (i.e., non-POSIX platforms like Windows/WASI don't expose os.getegid/os.geteuid). Helps future readers avoid confusion.

Once the CLA is signed this should be good to go. Thanks for the contribution!