[CI] Switch to parallel build config for coveralls

[alyssadai]

• Closes Investigate Coveralls failure about "parallel builds" #238 (hopefully 🤞)

Changes proposed in this pull request:

• Switched to the recommended Coveralls config for parallel builds following:
  • https://github.com/marketplace/actions/coveralls-github-action#complete-parallel-job-example
  • this Python example: https://github.com/requests/requests-oauthlib/blob/master/.github/workflows/run-tests.yml

Checklist

• PR has an interpretable title with a prefix ([ENH], [FIX], [REF], [TST], [CI], [MNT], [INF], [MODEL], [DOC]) (see https://neurobagel.org/contributing/pull_requests for more info)
• PR links to GitHub issue with mention Closes #XXXX
• Tests pass
• Checks pass

For new features:

• Tests have been added

For bug fixes:

• There is at least one test that would fail under the original bug conditions.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b66b9ee) 97.86% compared to head (ba02970) 97.86%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #263   +/-   ##
=======================================
  Coverage   97.86%   97.86%           
=======================================
  Files          13       13           
  Lines         703      703           
=======================================
  Hits          688      688           
  Misses         15       15           

☔ View full report in Codecov by Sentry.
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[coveralls]

Pull Request Test Coverage Report for Build 7265175264

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 99.696%

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Totals
Change from base Build 7252899380:	0.0%
Covered Lines:	1311
Relevant Lines:	1315

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💛 - Coveralls

[surchs]

🧑‍🍳 very nice!

[surchs]

🚀 PR was released in v0.2.1 🚀