Added poetry integration.

Description:
* Fixed github actions;
* Removed requirements.txt;
* Fixed CONTRIBUTING.md;
* Fixed black and flake8.

Signed-off-by: Pavel <win10@list.ru>

tests/test_relations/test_prefetch_related_multiple_models_relation.py

@@ -95,6 +95,6 @@ async def test_add_students():
         assert user.attending is not None
         assert len(user.attending) > 0
 
-        query = Session.objects.prefetch_related(["students", "teacher",])
+        query = Session.objects.prefetch_related(["students", "teacher"])
         sessions = await query.all()
         assert len(sessions) == 5

tests/test_relations/test_select_related_with_limit.py

@@ -56,7 +56,7 @@ class SecondaryModel(ormar.Model):
     id: int = ormar.Integer(primary_key=True)
     name: str = ormar.String(max_length=100)
     primary_model: PrimaryModel = ormar.ForeignKey(
-        PrimaryModel, related_name="secondary_models",
+        PrimaryModel, related_name="secondary_models"
     )