autopkgtest failures for python-qwt 0.12.5-1

[Pushkar Kulkarni]

Imported from Debian bug http://bugs.debian.org/1074168:

Package: python-qwt
Version: 0.12.5-1
Severity: normal

The 0.12.5-1 version of python-qwt runs into autopkgtest failures (e.g
[1][2])

---
Testing with python3.12:
Traceback (most recent call last):
  File "/usr/bin/PythonQwt-tests", line 8, in <module>
    sys.exit(run())
             ^^^^^
  File "/usr/lib/python3/dist-packages/qwt/tests/__init__.py", line 27, in
run
    launcher = TestLauncher()
               ^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/qwt/tests/utils.py", line 147, in
__init__
    self.fill_layout()
  File "/usr/lib/python3/dist-packages/qwt/tests/utils.py", line 157, in
fill_layout
    for fname in get_tests(qwt):
                 ^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/qwt/tests/utils.py", line 98, in
get_tests
    _temp = __import__(test_package.__name__, fromlist=[module_name])
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/qwt/tests/test_highdpi.py", line 13,
in <module>
    import pytest
ModuleNotFoundError: No module named 'pytest'
---

Adding python3-test as a test-dependency should fix this.

[1] https://ci.debian.net/packages/p/python-qwt/testing/amd64/48057217/
[2]
https://objectstorage.prodstack5.canonical.com/swift/v1/AUTH_0f9aae918d5b4744bf7b827671c86842/autopkgtest-oracular/oracular/amd64/p/python-qwt/20240622_203407_3c2b5@/log.gz