[tox] Allowing running of specific tests (#9097)

tests/dashboard_tests.py

@@ -14,6 +14,7 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
+# isort:skip_file
 """Unit tests for Superset"""
 import json
 import unittest
@@ -22,6 +23,7 @@ from random import random
 from flask import escape
 from sqlalchemy import func
 
+import tests.test_app
 from superset import db, security_manager
 from superset.connectors.sqla.models import SqlaTable
 from superset.models import core as models