The rational function $f$ is defined by an equation in the form $f(x)=\frac{a}{x+b}$, where $a$ and $b$ are constants. The graph of $y=f(x)$ has a vertical asymptote at $x=-3$. If $g(x)=f(x-5)$, what is the equation of the vertical asymptote of $y=g(x)$?