Merge pull request #530 from jack-w-shaw/JUJU-4184_tf_check_job

#530

## Description

The check target is a special target used in our CI.

This should allow our default Jenkins jobs to correctly run our unit tests and merge

## Type of change

- Change in tests (one or several tests have been changed)
- Maintenance work (repository related, like Github actions, or revving the Go version, etc.)

## QA steps

commenting `/build` or `/merge` correctly trigger jenkins jobs

Makefile

@@ -102,5 +102,4 @@ install-snap-dependencies: check-snap-package
 install-dependencies: install-snap-dependencies
 ## install-dependencies: Install all the dependencies
 
-
-
+check: juju-unit-test