Let \( A(1,0) \), \( B(2,-1) \) and \( C\!\left(\frac{7}{3}, \frac{4}{3}\right) \) be three points. If the equation of the bisector of the angle \( ABC \) is \( \alpha x + \beta y = 5 \), then the value of \( \alpha^2 + \beta^2 \) is:
\( 13 \)
\( 8 \)
\( 10 \)
\( 5 \)