use openql from pip again

[wvlothuizen]

Please use the following template for a pull request.

Fixes #issuenumber.

Changes proposed in this pull request:

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In order for the pull request to be merged, the following conditions must be met:

• test suite (Github actions) passes
• all reasonable issues raised by codacy must be resolved
• a positive review is required

Whenever possible the pull request should

• follow the PEP8 style guide
• have tests for the code
• be well documented and contain comments

Tests are not mandatory as this is generally hard to make for instruments that interact with hardware.

[codecov-commenter]

Codecov Report

Merging #647 (bbab46e) into develop (5338c51) will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #647   +/-   ##
========================================
  Coverage    32.72%   32.72%           
========================================
  Files          316      316           
  Lines        69211    69211           
========================================
  Hits         22651    22651           
  Misses       46560    46560           

Impacted Files	Coverage Δ
...measurement/openql_experiments/generate_CCL_cfg.py	100.00% <100.00%> (ø)

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