support newer venv and virtualenv

since real_prefix is no longer set

Author: Taaku18

cogs/plugins.py

@@ -187,7 +187,7 @@ async def load_plugin(self, plugin):
         if req_txt.exists():
             # Install PIP requirements
 
-            venv = hasattr(sys, "real_prefix")  # in a virtual env
+            venv = hasattr(sys, "real_prefix") or hasattr(sys, "base_prefix") # in a virtual env
             user_install = " --user" if not venv else ""
             proc = await asyncio.create_subprocess_shell(
                 f"{sys.executable} -m pip install --upgrade{user_install} -r {req_txt} -q -q",