fix: adjust TestPolicyAccess::test_get_by_name for riscv64

[cjwatson]

The older manylinux policies don't exist on this architecture.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.24%. Comparing base (4490469) to head (f28ab6b).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #662   +/-   ##
=======================================
  Coverage   95.24%   95.24%           
=======================================
  Files          22       22           
  Lines        1829     1829           
  Branches      343      343           
=======================================
  Hits         1742     1742           
  Misses         48       48           
  Partials       39       39           

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[mayeut]

Thanks,
Same suggestion for loongarch64 while this is being update.

Longer run (i.e. not for now), we'll need to check what we want to test with this and either simplify and/or parametrize rather than depend on architecture detection.