…t to braket

This modification allows users to convert their qiskit circuit object that was parametrized with a qiskit ParameterVector to convert it to a braket circuit.

By default, qiskit names elements of a ``ParameterVector`` are named like this 'a[<index>]'. The '[]' parentheses are not supported by the QASM 3 syntax which leads to an error when trying to run a Braket Circuit with free parameters following the '[]'-naming. Therefore, I ensured that these will be removed before the ``ParamterExpression`` is passed to create a FreeParameterExpression out of it.

…t ``ParameterVector``

Assume this example: A one-qubit qiskit circuit with the parametrized Rx-gate as its only operation.
When using a qiskit ``ParameterVector``` of length 1 (i.e., params = ParameterVector("a", 1)), this would lead to the Parameter being called 'a[0]' which leads to a QASM 3 syntax error when trying to run the circuit.
The proposed changes ensure that the squared-parentheses '[]' are being removed in the parameter names.