Add slow_test as it's no longer part of Qiskit 1.0 (backport #141)

[mergify[bot]]

This is an automatic backport of pull request #141 done by Mergify. Cherry-pick of 22452888e3b3cb5a8b2f08c7e262c5b8ec4bbdc4 has failed:

On branch mergify/bp/stable/0.2/pr-141
Your branch is up to date with 'origin/stable/0.2'.

You are currently cherry-picking commit 2245288.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
    modified:   test/__init__.py
    new file:   test/decorators.py
    modified:   test/eigensolvers/test_vqd.py
    modified:   test/gradients/test_estimator_gradient.py
    modified:   test/minimum_eigensolvers/test_sampling_vqe.py
    modified:   test/minimum_eigensolvers/test_vqe.py
    modified:   test/time_evolvers/test_pvqd.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
    both modified:   test/optimizers/test_optimizer_aqgd.py

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

---

Mergify commands and options

More conditions and actions can be found in the [documentation](https://docs.mergify.com/). You can also trigger Mergify actions by commenting on this pull request: - `@Mergifyio refresh` will re-evaluate the rules - `@Mergifyio rebase` will rebase this PR on its base branch - `@Mergifyio update` will merge the base branch into this PR - `@Mergifyio backport ` will backport this PR on `` branch Additionally, on Mergify [dashboard](https://dashboard.mergify.com) you can: - look at your merge queues - generate the Mergify configuration with the config editor. Finally, you can contact us on https://mergify.com

[coveralls]

Pull Request Test Coverage Report for Build 7801091811

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.03%) to 90.066%

---

Files with Coverage Reduction	New Missed Lines	%
qiskit_algorithms/gradients/reverse/reverse_gradient.py	3	94.67%
<!--	Total:	3		-->

Totals
Change from base Build 7785736705:	0.03%
Covered Lines:	6446
Relevant Lines:	7157

---

💛 - Coveralls