Update pip prior to installing aer (#3267)
Update pip prior to installing aer (#3267)

The new aer packages use manylinux2010, and the randomized testing job
is using the sdist instead of the wheel. This commit updates the pip
version prior to installing aer to try and get it to install the binary
version instead of the source package.
QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py