[lldb] Make IR interpreter timeout test more loose

This has failed once in a while on our Windows on Arm bot:
https://lab.llvm.org/buildbot/#/builders/219/builds/4688

Traceback (most recent call last):
  File "C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\...
    self.assertGreaterEqual(duration_sec, 1)
AssertionError: 0.9907491207122803 not greater than or equal to 1

We're not here to check that Python/the C++ lib/the OS implemented
timers correctly, so accept anything 0.95 or greater.