setup_pytest to find site-packages folder near sys.executable

Used to get errors running setup_pytest.py having python 3.10 installed on my pc (`sys_paths[-1]` was the system's python folder, not the blender's python).

src/blenderbim/scripts/setup_pytest.py

@@ -18,18 +18,20 @@
 
 import sys
 import subprocess
+from pathlib import Path
 
 print("Here are the detected system paths:")
 print(sys.path)
 
 py_exec = str(sys.executable)
+base_python_path = str(Path(sys.executable).parent.parent)  # path without bin/python.exe
 
 print("Detected executable:", py_exec)
 
 subprocess.call([py_exec, "-m", "ensurepip", "--user"])
 subprocess.call([py_exec, "-m", "pip", "install", "--upgrade", "pip"])
 
-sys_paths = [p for p in sys.path if "site-packages" in p]
+sys_paths = [p for p in sys.path if "site-packages" in p and p.startswith(base_python_path)]
 if sys_paths:
     print("Detected installation directory:", sys_paths[-1])
     subprocess.call([py_exec, "-m", "pip", "install", f"--target={sys_paths[-1]}", "--upgrade", "pytest"])