Change type guards to return never instead of false in option

Previously when invoking the `isSome` on None type or `isNone` on Some
type would return always false and the corresponding type would be set
as the original type. This however does not work with the newest
TypeScript version `5.5.3`. The failure in this case is correct as the
inference does not work as expected if a false is returned instead of a
type guard.

The 'correct' change here is to instead return never type guard as we
can never enter that block that checks for isNone or isSome on a type
that does not reflect it.

Example:
```ts
const some = Some(42);

// Previously this was accepted and the type was inferred as Some in the
// code block
if (some.isNone()) {
  some;
  // ^? Some<number>;
}

// However now the type would be never, which is less flexible, but
// correct behaviour
if (some.isNone()) {
  some;
  // ^? never
}
```

option/option.ts

@@ -686,7 +686,7 @@ export class Some<T> extends Option<T> {
   }
 
   /** {@link Option.isNone} */
-  isNone(): false {
+  isNone(): this is never {
     return false;
   }
 
@@ -757,7 +757,7 @@ export class None extends Option<never> {
   }
 
   /** {@link Option.isSome} */
-  isSome(): false {
+  isSome(): this is never {
     return false;
   }
 

option/option_test_types.ts

@@ -97,7 +97,7 @@ import { assertType, type IsExact } from "@std/testing/types";
   const option2 = Some(42);
 
   if (option2.isNone()) {
-    assertType<IsExact<typeof option2, Some<42>>>(true);
+    assertType<IsExact<typeof option2, never>>(true);
   }
 
   if (Option.isNone(option2)) {
@@ -123,7 +123,7 @@ import { assertType, type IsExact } from "@std/testing/types";
   }
 
   if (option3.isSome()) {
-    assertType<IsExact<typeof option3, None>>(true);
+    assertType<IsExact<typeof option3, never>>(true);
   }
 
   if (Option.isSome(option3)) {