Fix incompatibility with Pulsar

[JamesBasham]

Description

When pulsar and stim are both imported, RuntimeError is raised when iterating through a circuit

Steps to Reproduce

# This line somehow corrupts stim
import _pulsar  # The C++ module of pulsar

import stim
print(list(stim.Circuit()))  # RuntimeError: Index 0 not in range for sequence of length 0.

It does not seem to matter whether stim or pulsar is imported first.

Environment

ARM Mac
Python 3.10.18
Fresh pip env containing:

certifi==2025.8.3
numpy==2.2.6
pulsar-client==3.8.0
stim==1.15.0

Affected Versions

stim>1.5.0 (1.5.0 and earlier work)
All pulsar versions 3.0 and greater do not work (less than 3.0 not tested)