fix mistake in tests.yml made during backport

[grlee77]

Description

This mistake made during the backport in #6127 caused the GHA tests to be skipped. Hopefully they should be running again now!

Checklist

• Docstrings for all functions
• Gallery example in ./doc/examples (new features only)
• Benchmark in ./benchmarks, if your changes aren't covered by an
  existing benchmark
• Unit tests
• Clean style in the spirit of PEP8
• Descriptive commit messages (see below)

For reviewers

• Check that the PR title is short, concise, and will make sense 1 year
  later.
• Check that new functions are imported in corresponding __init__.py.
• Check that new features, API changes, and deprecations are mentioned in
  doc/release/release_dev.rst.

[grlee77]

The Azure job failures here are unrelated and apparently to be expected. The message says:

##[error]This is a scheduled windows-2016 brownout. The windows-2016 environment is deprecated and will be removed on March 15, 2022. For more details, see https://github.com/actions/virtual-environments/issues/4312
,##[error]The remote provider was unable to process the request.

So we just need to update the environment used for Azure in a separate PR to main and then backport that.

[hmaarrfk]

Feel free to merge this 1 liner!

[grlee77]

sure, just wanted to double-check that the tests do all pass on this branch!