A line and a circle intersect at $A$ and $B,$ as shown below. Find the coordinates of the midpoint of $\overline{AB}$.

[asy]
usepackage("amsmath");
usepackage("amssymb");

unitsize(2 cm);

pair A, B;

A = dir(240);
B = dir(330);

draw(Circle((0,0),1));
draw(interp(A,B,-0.5)--interp(A,B,1.5));

dot("$A$", A, S);
dot("$B$", B, SE);

label("$x^2 + y^2 = 6$", dir(45), NE);
label("$y = \dfrac{x - 4}{2}$", interp(A,B,1.5), E);
[/asy]