Fix breaking PBA file upload unit tests on windows.

The tests broke because `get` endpoint opened up the file handle which was not closed anywhere. The delete endpoint couldn't delete the file, since a process was using it.

monkey/tests/unit_tests/monkey_island/cc/resources/test_pba_file_upload.py

@@ -92,16 +92,19 @@ def test_pba_file_upload_endpoint(
         content_type="multipart/form-data; " "boundary=---------------------------" "1",
         follow_redirects=True,
     )
+
     resp_get = flask_client.get(f"/api/fileUpload/{pba_os}?load=test.py")
+    assert resp_get.status_code == 200
+    assert resp_get.data.decode() == "m0nk3y"
+    # Closing the response closes the file handle, else it can't be deleted
+    resp_get.close()
+
     resp_delete = flask_client.delete(
         f"/api/fileUpload/{pba_os}", data="test.py", content_type="text/plain;"
     )
     resp_get_del = flask_client.get(f"/api/fileUpload/{pba_os}?load=test.py")
     assert resp_post.status_code == 200
 
-    assert resp_get.status_code == 200
-    assert resp_get.data.decode() == "m0nk3y"
-
     assert resp_delete.status_code == 200
 
     assert resp_get_del.status_code == 404