Adjust version of required xsimd in README

change was imposed in c29ef19

Author: starboerg

README.md

@@ -97,7 +97,7 @@ library:
 
 | `xtensor` | `xtl`   |`xsimd` (optional) |
 |-----------|---------|-------------------|
-|  master   | ^0.7.5  |       ^8.0.3      |
+|  master   | ^0.7.5  |       ^10.0.0      |
 |  0.24.x   | ^0.7.0  |       ^8.0.3      |
 |  0.23.x   | ^0.7.0  |       ^7.4.8      |
 |  0.22.0   | ^0.6.23 |       ^7.4.8      |