Add target attributes to alltoallv

[DJDavies2]

Description

Add target attributes to relevant variables in alltoallv to prevent dangling pointer errors. Fix #99.

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 51.07%. Comparing base (86e0bd1) to head (39f1ae6).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #100   +/-   ##
========================================
  Coverage    51.07%   51.07%           
========================================
  Files           58       58           
  Lines         4854     4854           
  Branches       453      453           
========================================
  Hits          2479     2479           
  Misses        2375     2375           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[wdeconinck]

Thanks @DJDavies2 ! 🙏