isbn-verifier: Add test case with only 9 digits (#1221)

fixes #1216

```
  1 * 10
+ 3 * 9
+ 4 * 8
+ 4 * 7
+ 5 * 6
+ 6 * 5
+ 7 * 4
+ 2 * 3
+ 9 * 2
= 209
```

209 is divisible by 11.

Thus, an implementation that appends 0 will incorrectly accept this case.

Author: mikestratton

exercises/isbn-verifier/canonical-data.json

@@ -1,6 +1,6 @@
 {
     "exercise": "isbn-verifier",
-    "version": "2.3.0",
+    "version": "2.4.0",
     "comments": [
         "An expected value of true indicates a valid ISBN-10, ",
         "whereas false means the ISBN-10 is invalid."
@@ -117,6 +117,14 @@
               "isbn": ""
             },
             "expected": false
+        },
+        {
+            "description": "input is 9 characters",
+            "property": "isValid",
+            "input": {
+                "isbn": "134456729"
+            },
+            "expected": false
         }
     ]
 }