Deligne's generation conjecture for the Ihara graded Galois Lie algebra

Fix a prime number $\ell$. Let $G_{\mathbb Q}$ be the absolute Galois group of $\mathbb Q$, and let $I_\ell^\bullet G_{\mathbb Q}$ be Ihara's filtration induced by the outer action on the pro-$\ell$ completion of the fundamental group of $\mathbb P^1(\mathbb C)-\{0,1,\infty\}$. Write

$$\operatorname{Gr}^{>0}_{I_\ell}G_{\mathbb Q}=\bigoplus_{n>0}\operatorname{Gr}^n_{I_\ell}G_{\mathbb Q}$$

for its positive associated graded Lie algebra, and let $s_{2n+1}\in\operatorname{Gr}^{2n+1}_{I_\ell}G_{\mathbb Q}$.

Deligne's conjecture. The $\mathbb Q_\ell$-form

$$\left(\operatorname{Gr}^{>0}_{I_\ell}G_{\mathbb Q}\right)\otimes\mathbb Q_\ell$$

of the positive part of $\operatorname{Gr}^{\bullet}_{I_\ell}G_{\mathbb Q}$ is generated as a Lie algebra by the elements $s_3,s_5,s_7,\ldots$.

The conjecture concerns the structure of the graded Lie algebra arising from the Galois action on the pro-$\ell$ fundamental group of the thrice-punctured projective line. The paper states that this generation assertion is proved, but the supplied status is unknown.