improve fight logic with base stats

[LAMaglan]

Address https://github.com/LAMaglan/PokeFightSimulator/issues/29

Here is the logic of base stats:

def battle_simulator(pokemon1: Pokemon, pokemon2: Pokemon):
    if pokemon1.speed > pokemon2.speed:
        attacker = pokemon1
        defender = pokemon2
    else:
        attacker = pokemon2
        defender = pokemon1

    while pokemon1.hp > 0 and pokemon2.hp > 0:
        if attacker.attack > defender.defense:
            damage = attacker.attack - defender.defense
            defender.hp -= damage
        elif attacker.special_attack > defender.special_defense:
            damage = attacker.special_attack - defender.special_defense
            defender.hp -= damage
        attacker, defender = (
            defender,
            attacker,
        )  # Players switch roles for the next round

    if pokemon1.hp <= 0:
        return pokemon2.name
    else:
        return pokemon1.name

Also created a Pokemon class Note: since inherits from BaseModel, and Pokemon is not defining the attributes as class attributes, have to use

class Config:
        allow_mutation = False        

Note actually, allow_mutation was not necessary. See next PR