[Stable] Qiskit Aqua Release 0.8.2

[manoelmarques]

Summary

This commit prepares for the 0.8.2 release. This is just a bugfix release
that fixes breaking bugs since the 0.8.1 release.

Details and comments

Bugs fixed:

1. Fix for DOCplex 2.20 (Fix for docplex 2.20 #1520)
2. Remove dependency on internal DOCplex methods (Remove dependency on internal DOCplex methods. #1441)
3. Remove DeprecationWarning of np.int, np.float, np.bool, np.complex ( Remove DeprecationWarning of np.int, np.float, np.bool, np.complex #1517)
4. Fix Grover operator usage in AE (Fix Grover operator usage in AE #1502)
5. Add support for python 3.9 (Add support for Python 3.9 #1504)
6. Deal with both old and new locations of Var of docplex (Deal with both old and new locations of Var of docplex #1522)

[t-imamichi]

Please wait for #1522, qiskit-community/qiskit-optimization#24