Remove CHANGELOG.md and enforcer

[mathomp4]

This repo was constructed based on the gmao template repo which has the "usual" CHANGELOG.md file that we prefer. However, @gmao-rreichle has handled his changelogs in GEOSldas in a different way and he might want to do that here as well.

So, this PR removes the CHANGELOG.md and enforcer from this repo. They can be added back if needed later.

[gmao-rreichle]

@mathomp4:
Thanks for creating the PR. Upon further reflection, I think we should keep and enforce the CHANGELOG.
I'm envisioning that developers should contribute to the GEOSldas_GridComp CHANGELOG.
For new releases of the GEOSldas fixture, I'll then curate these changes into the existing GEOSldas/doc/CHANGELOG.md file.
Closing this PR.