fix how runtime dependencies are added to sys.path

start.py

@@ -131,7 +131,21 @@
 # Vendored python modules that must not be in PYTHONPATH environment but
 #   are required for OpenPype processes
 vendor_python_path = os.path.join(OPENPYPE_ROOT, "vendor", "python")
-sys.path.insert(0, vendor_python_path)
+runtime_site_packages = []
+if platform.system().lower() == "windows":
+    runtime_site_packages.append(os.path.join(
+        vendor_python_path, "Lib", "site-packages"
+    ))
+else:
+    lib_dir = os.path.join(vendor_python_path, "lib")
+    # linux and macos create python{x}.{y} subfolder with 'site-packages'
+    for name in os.listdir(lib_dir):
+        site_packages = os.path.join(lib_dir, name, "site-packages")
+        if os.path.exists(site_packages):
+            runtime_site_packages.append(site_packages)
+
+for runtime_site_package in runtime_site_packages:
+    sys.path.insert(0, runtime_site_package)
 
 # Add common package to sys path
 # - common contains common code for bootstraping and OpenPype processes