test: align demonstration canonical input count with V38

Update the demonstration specifying test's active-canon artifact-count map so V38 canonical input validation expects the current source truth of artifacts=0.

Validated with the targeted v21-specifying node test and diff hygiene.

Author: geraldarthurdavis

protocol-demonstration/test/v21-specifying.test.js

@@ -25,6 +25,7 @@ function expectedActiveCanonicalInputArtifactCount(version) {
     V35: 0,
     V36: 0,
     V37: 0,
+    V38: 0,
   };
   if (Object.hasOwn(expectedCountsByVersion, version)) {
     return expectedCountsByVersion[version];