Bump is-my-json-valid from 2.16.0 to 2.20.6 in /generator-exercise

Bumps [is-my-json-valid](https://github.com/mafintosh/is-my-json-valid) from 2.16.0 to 2.20.6.
- [Release notes](https://github.com/mafintosh/is-my-json-valid/releases)
- [Commits](https://github.com/mafintosh/is-my-json-valid/compare/v2.16.0...v2.20.6)

---
updated-dependencies:
- dependency-name: is-my-json-valid
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

generator-exercise/package-lock.json

@@ -1856,16 +1856,31 @@
         "is-extglob": "^1.0.0"
       }
     },
+    "is-my-ip-valid": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/is-my-ip-valid/-/is-my-ip-valid-1.0.1.tgz",
+      "integrity": "sha512-jxc8cBcOWbNK2i2aTkCZP6i7wkHF1bqKFrwEHuN5Jtg5BSaZHUZQ/JTOJwoV41YvHnOaRyWWh72T/KvfNz9DJg==",
+      "dev": true
+    },
     "is-my-json-valid": {
-      "version": "2.16.0",
+      "version": "2.20.6",
-      "resolved": "https://registry.npmjs.org/is-my-json-valid/-/is-my-json-valid-2.16.0.tgz",
+      "resolved": "https://registry.npmjs.org/is-my-json-valid/-/is-my-json-valid-2.20.6.tgz",
-      "integrity": "sha1-8Hndm/2uZe4gOKrorLyGqxCeNpM=",
+      "integrity": "sha512-1JQwulVNjx8UqkPE/bqDaxtH4PXCe/2VRh/y3p99heOV87HG4Id5/VfDswd+YiAfHcRTfDlWgISycnHuhZq1aw==",
       "dev": true,
       "requires": {
         "generate-function": "^2.0.0",
         "generate-object-property": "^1.1.0",
-        "jsonpointer": "^4.0.0",
+        "is-my-ip-valid": "^1.0.0",
+        "jsonpointer": "^5.0.0",
         "xtend": "^4.0.0"
+      },
+      "dependencies": {
+        "jsonpointer": {
+          "version": "5.0.1",
+          "resolved": "https://registry.npmjs.org/jsonpointer/-/jsonpointer-5.0.1.tgz",
+          "integrity": "sha512-p/nXbhSEcu3pZRdkW1OfJhpsVtW1gd4Wa1fnQc9YLiTfAjn0312eMKimbdIQzuZl9aa9xUGaRlP9T/CJE/ditQ==",
+          "dev": true
+        }
       }
     },
     "is-number": {
@@ -2965,12 +2980,6 @@
       "integrity": "sha1-LHS27kHZPKUbe1qu6PUDYx0lKnM=",
       "dev": true
     },
-    "jsonpointer": {
-      "version": "4.0.1",
-      "resolved": "https://registry.npmjs.org/jsonpointer/-/jsonpointer-4.0.1.tgz",
-      "integrity": "sha1-T9kss04OnbPInIYi7PUfm5eMbLk=",
-      "dev": true
-    },
     "jsprim": {
       "version": "1.4.1",
       "resolved": "https://registry.npmjs.org/jsprim/-/jsprim-1.4.1.tgz",