mark move @inlinable to better signal intent (swiftlang#78944)

Co-authored-by: Jaap Wijnen <[email protected]>

Author: JaapWijnen

stdlib/public/Differentiation/Differentiable.swift

@@ -40,6 +40,7 @@ public protocol Differentiable {
 
 public extension Differentiable where TangentVector == Self {
   @_alwaysEmitIntoClient
+  @inlinable
   mutating func move(by offset: TangentVector) {
     self += offset
   }