Update declaration of memory safe assembly blocks (#5172)

Signed-off-by: Hadrien Croubois <hadrien.croubois@gmail.com>

scripts/generate/templates/SafeCast.js

@@ -121,8 +121,7 @@ const boolToUint = `\
  * @dev Cast a boolean (false or true) to a uint256 (0 or 1) with no jump.
  */
 function toUint(bool b) internal pure returns (uint256 u) {
-    /// @solidity memory-safe-assembly
-    assembly {
+    assembly ("memory-safe") {
         u := iszero(iszero(b))
     }
 }