CompatHelper: add new compat entry for DimensionalData at version 0.30 for package test, (keep existing compat)

[github-actions]

This pull request sets the compat entry for the DimensionalData package to 0.30 for package test.
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.
Note: Consider registering a new release of your package immediately after merging this PR, as downstream packages may depend on this for tests to pass.

[github-actions]

AbstractPPL.jl documentation for PR #153 is available at:
https://TuringLang.github.io/AbstractPPL.jl/previews/PR153/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.29%. Comparing base (f81b104) to head (8a60bcc).
⚠️ Report is 1 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (f81b104) and HEAD (8a60bcc). Click for more details.

HEAD has 2 uploads less than BASE

Flag	BASE (f81b104)	HEAD (8a60bcc)
	5	3

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #153      +/-   ##
==========================================
- Coverage   84.49%   79.29%   -5.20%     
==========================================
  Files          10        9       -1     
  Lines         561      541      -20     
==========================================
- Hits          474      429      -45     
- Misses         87      112      +25     

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