CI: measure coverage in Python subprocesses via patch = subprocess

Tests such as test_helptext and test_shell_completion run `dandi` as a
subprocess, so the CLI code they exercise was never recorded.  coverage's
`patch = subprocess` starts measurement in child Python processes, writing
parallel data files that the existing `coverage combine` picks up.  Bump the
floor to coverage 7.10.6, which carries fixes for this feature.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UkDjoCcCmBNuhFkmTyyohk

Author: claude

pyproject.toml

@@ -105,7 +105,8 @@ extras = [
 test = [
     "aiohttp >= 3.8.4, < 3.14",  # See https://github.com/kevin1024/vcrpy/issues/995
     "anys ~= 0.3",
-    "coverage >= 7.0.0",
+    # 7.10.6 has fixes for `patch = subprocess` (see tox.ini)
+    "coverage >= 7.10.6",
     # 4.10.0.84 first built for numpy 2.x ABI (older wheels segfault under numpy 2)
     # Workaround for VideoWriter regression in 4.13.0.90 on Intel macOS
     "opencv-python >= 4.10.0.84, < 4.13 ; sys_platform == 'darwin' and platform_machine != 'arm64'",

tox.ini

@@ -91,6 +91,8 @@ filterwarnings =
 
 [coverage:run]
 parallel = True
+# Also measure Python subprocesses, e.g. tests invoking the `dandi` CLI
+patch = subprocess
 source = dandi
 
 [coverage:report]