Solution (source code)

= Solution

There are
$$
\boxed{0}
$$
such conjugacy classes. Every matrix in $GL_{10}(\mathbb Q)$ is an <invertible matrix>, so by the <minimal polynomial of an invertible matrix> its minimal polynomial must have nonzero constant term. But
$$
X^7-4X^3=X^3(X^4-4)
$$
has constant term zero and cannot be the minimal polynomial of an invertible matrix.