Remove qiskit_machine_learning direct dependency (#95)

* Remove qiskit_machine_learning direct dependency

* Increment python_requires to 3.7 minimum

Author: gcattan

setup.py

@@ -32,14 +32,13 @@
           'Tracker': 'https://github.com/pyRiemann/pyRiemann-qiskit/issues/',
       },
       platforms='any',
-      python_requires=">=3.6",
+      python_requires=">=3.7",
       install_requires=['cython', 'pyriemann==0.3',
-                        'qiskit_machine_learning @ git+https://github.com/Qiskit/qiskit-machine-learning#egg=qiskit_machine_learning',
+                        'qiskit_machine_learning==0.5.0',
                         'qiskit-ibmq-provider==0.19.2',
                         'qiskit-optimization==0.4.0',
                         'cvxpy==1.2.3',
-                        'scipy==1.5.4; python_version < "3.7.0"',
-                        'scipy==1.7.3; python_version >= "3.7.0"',
+                        'scipy==1.7.3',
                         'docplex>=2.21.207',
                         'firebase_admin==6.0.1',
                         'tqdm'