Feat: add add_tribe in service

tests/model/fakes.py

@@ -91,35 +91,3 @@ def build_student(
             Student(name=faker.name(), tribe=tribe) for _ in range(students_per_tribe)
         ]
     return students
-
-
-class FakeTribeRepository(AbstractRepository):
-    def __init__(self, tribes):
-        self._tribes = {t.name: t for t in tribes}
-
-    def add(self, tribe):
-        if tribe.name not in self._tribes.keys():
-            self._tribes[tribe.name] = tribe
-        raise KeyError(f"{tribe} already exists")
-
-    def update(self, name, tribe):
-        try:
-            self._tribes.pop(name)
-            self._tribes[tribe.name] = tribe
-        except KeyError:
-            raise KeyError(f"The tribe {tribe} does not exists")
-
-    def list(self):
-        return list(self._tribes.values())
-
-    def get(self, name):
-        try:
-            return self._tribes[name]
-        except KeyError:
-            raise KeyError(f"The tribe {tribe} does not exists")
-
-    def delete(self, name):
-        try:
-            self._tribes.pop(name)
-        except KeyError:
-            raise KeyError(f"The tribe {tribe} does not exists")