Added isort config; linter now checks tests

tests/__init__.py

@@ -0,0 +1 @@
+"""Main testing module."""

tests/test_skeleton.py

@@ -1,15 +1,13 @@
 """Tests wether the skeleton merge works."""
-from app.skeleton import merge_with_skeleton
-from app.exceptions import InvalidKeyError, MissingKeyError
 import pytest
 
+from app.exceptions import InvalidKeyError, MissingKeyError
+from app.skeleton import merge_with_skeleton
+
 
 def test_single_invalid_key():
     """Tests wether an InvalidKeyError is correctly thrown for a single key."""
-    data = {
-        "test": 1,
-        "test2": "test"
-    }
+    data = {"test": 1, "test2": "test"}
     skel = {
         "test": None,
     }