Fix use of Self

See rust-lang/rust#69611.

This is necessary because

> Using `Self` should always refer to the `Self` type, just as using
> `Self {...}` would. In other words, your code should never have
> compiled.

This'll fix the recurring build failure on nightly Rusts.

Signed-off-by: Kristofer Rye <[email protected]>

src/vec.rs

@@ -32,7 +32,7 @@ where
 	type Output = Vec3d<T>;
 
 	fn mul(self, scalar: T) -> Vec3d<T> {
-		Self(
+		Vec3d(
 			scalar * self.0.into(),
 			scalar * self.1.into(),
 			scalar * self.2.into(),