Tests crash on pypy

Here's output from a recent run:

  tox
  shell: /usr/bin/bash -e {0}
  env:
    pythonLocation: /opt/hostedtoolcache/PyPy/3.9.12/x64
    Python_ROOT_DIR: /opt/hostedtoolcache/PyPy/3.9.12/x64
    Python2_ROOT_DIR: /opt/hostedtoolcache/PyPy/3.9.12/x64
    Python3_ROOT_DIR: /opt/hostedtoolcache/PyPy/3.9.12/x64
    PKG_CONFIG_PATH: /opt/hostedtoolcache/PyPy/3.9.12/x64/bin/lib/pkgconfig
python create: /home/runner/work/cmdix/cmdix/.tox/python
python installdeps: pytest >= 6.2.1
python develop-inst: /home/runner/work/cmdix/cmdix
ERROR: invocation failed (exit code -9), logfile: /home/runner/work/cmdix/cmdix/.tox/python/log/python-3.log
================================== log start ===================================

=================================== log end ====================================
___________________________________ summary ____________________________________
ERROR:   python: InvocationError for command /home/runner/work/cmdix/cmdix/.tox/python/bin/python -m pip freeze (exited with code -9 (SIGKILL)) (exited with code -9)

The process doesn't always fail precisely that way. Here's output from an earlier run:

  tox
  shell: /usr/bin/bash -e {0}
  env:
    pythonLocation: /opt/hostedtoolcache/PyPy/3.9.12/x64
    Python_ROOT_DIR: /opt/hostedtoolcache/PyPy/3.9.12/x64
    Python2_ROOT_DIR: /opt/hostedtoolcache/PyPy/3.9.12/x64
    Python3_ROOT_DIR: /opt/hostedtoolcache/PyPy/3.9.12/x64
    PKG_CONFIG_PATH: /opt/hostedtoolcache/PyPy/3.9.12/x64/bin/lib/pkgconfig
python create: /home/runner/work/cmdix/cmdix/.tox/python
python installdeps: pytest >= 6.2.1
python develop-inst: /home/runner/work/cmdix/cmdix
/home/runner/work/_temp/8f22a1bd-6a25-45f6-9a61-1150bb55390b.sh: line 1:  1706 Killed                  tox
Error: Process completed with exit code 137.

Start by inspecting the GitHub Actions run linked in the issue and the tox invocation that creates the PyPy environment. Reproduce the failure with the reported PyPy version, pytest dependency, and pip freeze step, then determine why the process is killed. Done means the test job completes successfully on PyPy without the reported SIGKILL or exit 137.