Fix crossplatform changes in type tests

Author: A5rocks

src/trio/_tests/type_tests/subprocesses.py

@@ -9,13 +9,15 @@ async def test() -> None:
     await trio.run_process("python", executable="ls")
     await trio.lowlevel.open_process("python", executable="ls")
 
+    # note: there's no error code on the type ignore as it varies
+    # between platforms.
     await trio.run_process("python", capture_stdout=True)
-    await trio.lowlevel.open_process("python", capture_stdout=True)  # type: ignore[call-arg]
+    await trio.lowlevel.open_process("python", capture_stdout=True)  # type: ignore
 
     if sys.platform != "win32" and sys.version_info >= (3, 9):
         await trio.run_process("python", extra_groups=[5])
         await trio.lowlevel.open_process("python", extra_groups=[5])
 
         # 3.11+:
-        await trio.run_process("python", process_group=5)  # type: ignore[call-arg]
-        await trio.lowlevel.open_process("python", process_group=5)  # type: ignore[call-arg]
+        await trio.run_process("python", process_group=5)  # type: ignore
+        await trio.lowlevel.open_process("python", process_group=5)  # type: ignore