Constrain qiskit versions in tox.ini (#927)

* Constrain qiskit versions in tox.ini

* Simplify imports with requirements

Author: edoaltamura

tox.ini

@@ -13,9 +13,7 @@ setenv =
   LANGUAGE=en_US
   LC_ALL=en_US.utf-8
   ARGS="-V"
-deps = git+https://github.com/Qiskit/qiskit.git
-       git+https://github.com/Qiskit/qiskit-aer.git
-       -r{toxinidir}/requirements.txt
+deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/requirements-dev.txt
        torch
        sparse