Fix #8992 (SparsePauliOp.dot with real coefficients)

[ikkoham]

Summary

Fix SparsePauliOp.dot between operators with real coefficients.
To fix this, the dtype that SparsePauliOp can take is restricted to
np.complex128 and object.

Fix #8992

Details and comments

[qiskit-bot]

Thank you for opening a new pull request.

Before your PR can be merged it will first need to pass continuous integration tests and be reviewed. Sometimes the review process can be slow, so please be patient.

While you're waiting, please feel free to review other open PRs. While only a subset of people are authorized to approve pull requests for merging, everyone is encouraged to review open pull requests. Doing reviews helps reduce the burden on the core team and helps make the project's code better for everyone.

One or more of the the following people are requested to review this:

• @Qiskit/terra-core
• @ikkoham

[coveralls]

Pull Request Test Coverage Report for Build 3325384445

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 84.404%

---

Totals
Change from base Build 3324535595:	0.03%
Covered Lines:	61734
Relevant Lines:	73141

---

💛 - Coveralls