TST: always set a (long) timeout for subprocess

If you are using this and really need unbounded timeouts, explicitly
pass `timeout=None`

Author: tacaswell

lib/matplotlib/testing/__init__.py

@@ -50,7 +50,7 @@ def setup():
     set_reproducibility_for_testing()
 
 
-def subprocess_run_for_testing(command, env=None, timeout=None, stdout=None,
+def subprocess_run_for_testing(command, env=None, timeout=60, stdout=None,
                                stderr=None, check=False, text=True,
                                capture_output=False):
     """