Update pytest and pytest-sugar, fix test for

- Teemu/pytest-sugar#188 makes pytest-sugar compatible with pytest 5.4+
- pytest 5.4.0 flipped the signs for assert statement display, so this flips the string to match.

tests/requirements.txt

@@ -7,8 +7,8 @@ isort==4.3.21
 mypy==0.761
 pycodestyle==2.5.0
 pyflakes==2.1.1
-pytest==5.4.0
+pytest==5.4.1
 pytest-cov==2.8.1
 pytest-mock==2.0.0
-pytest-sugar==0.9.2
+git+https://github.com/Teemu/pytest-sugar@refs/pull/188/merge
 twine==3.1.1

tests/test_validators.py

@@ -713,7 +713,7 @@ def check_a(cls, v):
 
     with pytest.raises(ValidationError) as exc_info:
         Model(a='snap')
-    injected_by_pytest = "\nassert 'snap' == 'a'\n  - snap\n  + a"
+    injected_by_pytest = "\nassert 'snap' == 'a'\n  - a\n  + snap"
     assert exc_info.value.errors() == [
         {'loc': ('a',), 'msg': f'invalid a{injected_by_pytest}', 'type': 'assertion_error'}
     ]