Fix failing test test_job_task_linter_library_not_installed_cluster (#2867)

## Changes
Use genuinely unknown library

### Linked issues
None

### Functionality
None

### Tests
- [ x] updated integration tests

---------

Co-authored-by: Eric Vergnaud <[email protected]>

Author: ericvergnaud

tests/integration/source_code/test_jobs.py

@@ -86,7 +86,7 @@ def test_job_task_linter_library_not_installed_cluster(
     created_cluster = make_cluster(single_node=True)
     entrypoint = make_directory()
 
-    notebook = make_notebook(path=f"{entrypoint}/notebook.ipynb", content=b"import greenlet")
+    notebook = make_notebook(path=f"{entrypoint}/notebook.ipynb", content=b"import library_not_found")
 
     task = jobs.Task(
         task_key=make_random(4),
@@ -100,7 +100,9 @@ def test_job_task_linter_library_not_installed_cluster(
 
     problems, *_ = simple_ctx.workflow_linter.lint_job(j.job_id)
 
-    assert len([problem for problem in problems if problem.message == "Could not locate import: greenlet"]) == 1
+    assert (
+        len([problem for problem in problems if problem.message == "Could not locate import: library_not_found"]) == 1
+    )
 
 
 def test_job_task_linter_library_installed_cluster(