[python] `TraceProcessor` fails to instantiate when downloading the perfetto shell under vscode's debugger.

Hey 👋

Whilst using the python perfetto package, I ran into an unhandled exception that occured during the instantiation of a `TraceProcessor`, more specifically, when the trace processor attempted to download the perfetto shell under vscode's python debugger.

[The contents of the exception may be seen here](https://github.com/lucamuscat/python-perfetto-vscode-bug-repro/blob/master/error_log.txt).

# Steps to reproduce
I created a minimal reproduction of the bug to aid with your investigation, which you may find [here](https://github.com/lucamuscat/python-perfetto-vscode-bug-repro/tree/master). The following are the steps to reproduce the bug using the provided MVP.

1. Clone the git repository containing the MVP: `git clone https://github.com/lucamuscat/python-perfetto-vscode-bug-repro.git`;
2. Open the workspace in vscode;
3. Run the `Reproduce bug` debug profile from the `Run and Debug` sidebar item.