Upgrade the CLI to v0.17.3 or later, which contains the fix. If you pin the CLI version in CI (and you should), bump the pin rather than unpinning to latest, so the next bad release cannot surprise you the same way. The maintainer also notes their end-to-end tests were improved to catch this class of packaging error, so staying on a recent fixed release is the durable answer.

Context: GitHub issue hashicorp/terraform-cdk#3025 (closed, 14 comments): every cdktf-cli command, including cdktf plan in GitHub Actions, suddenly fails with a file not found error for cli-core/templates, on multiple operating systems, with no changes to the infrastructure code. Maintainer ansgarm confirms it is a CLI packaging bug and points at the fix release.