fix: shell=True seems to be broken on non-Windows

With shell=True, it's better to provide a str rather than list[str].

From docs: "On POSIX with shell=True, (...) If args is a sequence, the first item specifies the command string, and any additional items will be treated as additional arguments to the shell itself.". On Windows there's automatic conversion, which might be undesired.

@see https://stackoverflow.com/questions/3172470/actual-meaning-of-shell-true-in-subprocess

Signed-off-by: Jack Cherng <jfcherng@gmail.com>

plugin.py

@@ -233,10 +233,10 @@ def binary_from_python_path(path: str) -> Optional[str]:
 
         # Config file, venv resolution command, post-processing
         venv_config_files = [
-            ("Pipfile", ["pipenv", "--py"], None),
-            ("poetry.lock", ["poetry", "env", "info", "-p"], binary_from_python_path),
-            (".python-version", ["pyenv", "which", "python"], None),
-        ]  # type: List[Tuple[str, List[str], Optional[Callable[[str], Optional[str]]]]]
+            ("Pipfile", "pipenv --py", None),
+            ("poetry.lock", "poetry env info -p", binary_from_python_path),
+            (".python-version", "pyenv which python", None),
+        ]  # type: List[Tuple[str, str, Optional[Callable[[str], Optional[str]]]]]
 
         for config_file, command, post_processing in venv_config_files:
             full_config_file_path = os.path.join(workspace_folder, config_file)