Pin numpy in `test_wheels.sh`

[JCGoran]

Required to make https://github.com/neuronsimulator/nrn-build-ci/pull/69 green.

[azure-pipelines[bot]]

✔️ 7b6ee0e46e56153350927475aea768de71007c01 -> Azure artifacts URL

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 67.22%. Comparing base (c5c0833) to head (7b6ee0e). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2919 +/- ## ========================================== - Coverage 67.22% 67.22% -0.01% ========================================== Files 569 569 Lines 104699 104696 -3 ========================================== - Hits 70381 70378 -3 Misses 34318 34318 ```

:umbrella: View full report in Codecov by Sentry.
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[bbpbuildbot]

Logfiles from GitLab pipeline #217557 (:white_check_mark:) have been uploaded here!

Status and direct links:

• :white_check_mark: mac_m1_cmake_build: [cmake, ON, OFF, OFF, address]
• :white_check_mark: spack_setup
• :white_check_mark: build:nmodl
• :white_check_mark: build:neuron:nmodl:intel:legacy
• :white_check_mark: build:neuron:nmodl:intel:shared
• :white_check_mark: build:neuron:nmodl:nvhpc:acc:legacy
• :white_check_mark: build:neuron:nmodl:nvhpc:acc:shared
• :white_check_mark: build:neuron:nmodl:nvhpc:omp:legacy
• :white_check_mark: build:neuron:nmodl:nvhpc:omp
• :white_check_mark: test:neuron:nmodl:intel:legacy
• :white_check_mark: test:neuron:nmodl:intel:shared
• :white_check_mark: test:neuron:nmodl:nvhpc:acc:legacy
• :white_check_mark: test:neuron:nmodl:nvhpc:acc:shared
• :white_check_mark: test:neuron:nmodl:nvhpc:omp:legacy
• :white_check_mark: test:neuron:nmodl:nvhpc:omp