Fix qutechopenql build fail during CI

[MiniSean]

One (of many) steps to address CI failing (develop 33c8dbd).

• CI fails when installing qutechopenql version from source: pip install qutechopenql --verbose --verbose --verbose --no-index -f https://github.com/DiCarloLab-Delft/OpenQL/releases
• Provided exception (more info see here): DistributionNotFound: No matching distribution found for qutechopenql

• When running a downgraded version requirement of qutechopenql (0.10.0, PyPI available), the following runtime errors appear: RuntimeError: Internal compiler error: Error in JSON definition: key 'cc' not found on path 'instructions/_fluxdance_1', actual node contents '{"decomposition":{"into":"{ cz q[10],q[8] | cz q[9],q[12] }"},"duration":0,"prototype":[]}'

• [x] Answer why qutechopenql >= 0.10.3 is a hard requirement?
• [x] Fix qutechopenql install from source release/latest. or
• [ ] Fix internal compiler errors while working with qutechopenql 0.10.0.

[MiniSean]

Hi @wvlothuizen, I would like to know why qutechopenql >= 0.10.3 is a hard requirement for pycqed and if it is possible to get away with version 0.10.0?

[wvlothuizen]

0.10.0 on PyPi is the last official release that doesn't contain any recent updates to the CC backend. Development releases are done in this repository, and the interaction with requirements.txt is a bit flaky.

It may be possible to increase the frequency of official releases, since access to PyPi by the official development team has recently be regained.

[MiniSean]

Having an official release would certainly make the installation process more reliable. But until then, I want to find a solution for installing from source during CI. Any suggestions? Who are the other other official development teams? Maybe I can see how they handle this issue.