use always the newest pip in new virtual environments?

Very often python comes with an old pip version which may produce different kinds of problems. After using `pip` command in a fresh virtual environment, user usually sees a text like this:

```
WARNING: You are using pip version 20.2.1; however, version 21.3.1 is available.
You should consider upgrading via the 'c:\python\venvs\someproj\scripts\python.exe -m pip install --upgrade pip' command.
```

it might be actually handy to have the `venvlink` new venv creation process to automatically do this. This could be also an option in the venvlinkrc.