CompatHelper: bump compat for "MPI" to "0.18"

[github-actions]

This pull request changes the compat entry for the MPI package from 0.17.2 to 0.17.2, 0.18.

This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.

[coveralls]

Pull Request Test Coverage Report for Build 873612588

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 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 54.892%

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Totals
Change from base Build 806884631:	0.0%
Covered Lines:	1425
Relevant Lines:	2596

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💛 - Coveralls

[codecov]

Codecov Report

Merging #64 (cb85916) into main (0a7f837) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #64   +/-   ##
=======================================
  Coverage   72.39%   72.39%           
=======================================
  Files          26       26           
  Lines        1945     1945           
=======================================
  Hits         1408     1408           
  Misses        537      537           

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