Do not allow $fillable usage (use $guarded instead)

[mantas-done]

Q	A
Bug report?	no
Feature request?	yes
Library version	x.y.z

New rule request. Do not allow $fillable usage (use $guarded instead).

[achrafAa]

Best Practices:

• Use $fillable when you have a small number of attributes that need to be mass-assigned. It’s more secure because it explicitly defines what can be assigned.

• Use $guarded when you have many attributes and only a few need to be restricted. It’s more convenient but less explicit.

• Avoid using $guarded = [] (allowing all attributes) unless you fully trust the input data, as it can lead to security vulnerabilities.