Azuma for a random walk with drift

Let $Y_1,Y_2,\dots$ be adapted to a filtration with $|Y_k|\le1$ and $\E[Y_k\mid\mathcal F_{k-1}] = \mu_k$, where $\mu_k$ is $\mathcal F_{k-1}$-measurable. Set $S_n = \sum_{k\le n}Y_k$ and $M_n = \sum_{k\le n}\mu_k$. Prove that

$$\P\big(S_n - M_n \ge t\big) \le \exp\left(-\frac{t^2}{8n}\right).$$

Note carefully that the $Y_k$ are neither independent nor identically distributed.