CompatHelper: bump compat for DynamicPPL to 0.15, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the DynamicPPL package from 0.14 to 0.14, 0.15.
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.

[codecov]

Codecov Report

Merging #1693 (30861e6) into master (98689ca) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1693   +/-   ##
=======================================
  Coverage   81.32%   81.32%           
=======================================
  Files          23       23           
  Lines        1392     1392           
=======================================
  Hits         1132     1132           
  Misses        260      260           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 98689ca...30861e6. Read the comment docs.

[coveralls]

Pull Request Test Coverage Report for Build 1178061913

• 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 81.322%

---

Totals
Change from base Build 1175387162:	0.0%
Covered Lines:	1132
Relevant Lines:	1392

---

💛 - Coveralls