New issue by angus-parvis on void-packages repository

https://github.com/void-linux/void-packages/issues/17799

Description:
<!-- Don't request update of package. We have a script for that. https://alpha.de.repo.voidlinux.org/void-updates/void-updates.txt . However, a quality pull request may help. -->
### System

* xuname:  
  *Void 5.3.18_1 x86_64 GenuineIntel uptodate rFFF*
* package:  
  *wpull-2.0.3_2*

### Expected behavior
I can successfully update wpull package.
### Actual behavior
On `xbps-install -Suv`, I got
```
wpull-2.0.3_2: configuring ...
Byte-compiling python3.8 code for module wpull...
*** Error compiling 'usr/lib/python3.8/site-packages/wpull/application/app_test.py'...
  File "usr/lib/python3.8/site-packages/wpull/application/app_test.py", line 5
    import wpull.testing.async
                         ^
SyntaxError: invalid syntax

*** Error compiling 'usr/lib/python3.8/site-packages/wpull/application/hook_test.py'...
  File "usr/lib/python3.8/site-packages/wpull/application/hook_test.py", line 7
    from wpull.testing.async import AsyncTestCase
                       ^
SyntaxError: invalid syntax

*** Error compiling 'usr/lib/python3.8/site-packages/wpull/driver/phantomjs_test.py'...
  File "usr/lib/python3.8/site-packages/wpull/driver/phantomjs_test.py", line 6
    import wpull.testing.async
                         ^
SyntaxError: invalid syntax

*** Error compiling 'usr/lib/python3.8/site-packages/wpull/driver/process.py'...
  File "usr/lib/python3.8/site-packages/wpull/driver/process.py", line 56
    self._stderr_reader = asyncio.async(self._read_stderr())
                                  ^
SyntaxError: invalid syntax
```
and the same error in 19 more files.
### Steps to reproduce the behavior
```
sudo xbps-install wpull
```