Characteristic polynomials of the curve $y^2=x^7+ax^4+bx$ over finite fields

In this work, we list all possible characteristic polynomials of the Frobenius endomorphism for genus $3$ hyperelliptic curves of type $y^2 = x^7 + a x^4 + b x$ over finite field $\mathbb{F}_q$ of characteristic $p>3$.