CI: Fix merge to main subprocess failure

news/fix-mtm.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* No news added.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>

tests/conftest.py

@@ -1,4 +1,5 @@
 import json
+import os
 import subprocess
 from pathlib import Path
 
@@ -10,14 +11,18 @@
 def conda_env(tmp_path):
     env_dir = tmp_path / "fake_env"
     env_dir_str = env_dir.as_posix()
+    shell = os.name == "nt"
     subprocess.run(
         ["conda", "create", "-y", "-p", env_dir_str],
         check=True,
         capture_output=True,
+        shell=shell,
     )
     yield env_dir_str
     subprocess.run(
-        ["conda", "env", "remove", "-p", env_dir_str, "-y"], check=True
+        ["conda", "env", "remove", "-p", env_dir_str, "-y"],
+        check=True,
+        shell=shell,
     )