Prove that the matrix \[ A = \begin{bmatrix} 2 & 3 \\ 1 & 2 \end{bmatrix} \] satisfies the equation \[ A^{2} - 4A + I_{2} = 0, \] where $I_{2}$ is the $2 \times 2$ identity matrix and $0$ is the $2 \times 2$ zero matrix. Also, find $A^{-1}$ with the help of this.