Set MACOSX_DEPLOYMENT_TARGET in CI to avoid extra warnings

[pramodk]

• In CI logs, we see the warnings like below (see this comment and CI log):

ld: warning: ld: warning: object file (x86_64/corenrn/build/libcoreneuron-core/capac.cpp.o) was built for newer macOS version (12.7) than being linked (12.0)
object file (x86_64/corenrn/build/libcoreneuron-core/abort.cpp.o) was built for newer macOS version (12.7) than being linked (12.0)
...

• Discussion here suggests upgrading CommandLineTools should solve the issue.
• As this is for CI runners, I think it's OK to just set latest/compatible deployment target.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[bbpbuildbot]

Logfiles from GitLab pipeline #218930 (: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

[codecov[bot]]

Codecov Report

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

Project coverage is 67.25%. Comparing base (00606f0) to head (1e56a13).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2944 +/- ## ======================================= Coverage 67.25% 67.25% ======================================= Files 571 571 Lines 104904 104893 -11 ======================================= - Hits 70552 70550 -2 + Misses 34352 34343 -9 ```

:umbrella: View full report in Codecov by Sentry.
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[azure-pipelines[bot]]

✔️ 1e56a134e3beb299e5a10ab6dcd86c51c6a3e736 -> Azure artifacts URL