Revert "Detect cedar-14 stack, or fail"
Revert "Detect cedar-14 stack, or fail"

This reverts commit 4581d0f07421603aef31a80b3e5b37ea2e2d40d0.

This change broke the buildpack upon release of the heroku-16 stack. In
lieu of an issue with a particular stack, we may want to remain open
to deployment to new stacks without requiring a change to the buildpack.

See https://github.com/dscout/wkhtmltopdf-buildpack/pull/16.

dscout/wkhtmltopdf-buildpack,teamkudoz/wkhtmltopdf-buildpack,tinfoil/heroku-buildpack-wkhtmltopdf