Upgrade to Qiskit Nature 0.6.0 (backport #24)

[mergify]

This is an automatic backport of pull request #24 done by Mergify.
Cherry-pick of 4ad204f has failed:

On branch mergify/bp/stable/0.1/pr-24
Your branch is up to date with 'origin/stable/0.1'.

You are currently cherry-picking commit 4ad204f.
  (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:   .pylintdict
	modified:   README.md
	modified:   docs/index.rst
	modified:   qiskit_nature_pyscf/qiskit_solver.py
	modified:   test/test_qiskit_solver.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   requirements.txt

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

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[mrossinek]

@Mergifyio refresh

[mergify]

refresh

✅ Pull request refreshed

[github-actions]

Pull Request Test Coverage Report for Build 4813407717

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 69.697%

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Totals
Change from base Build 3658002192:	0.0%
Covered Lines:	69
Relevant Lines:	99

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💛 - Coveralls