fix: adds ajv as an explicit dependency

Author: joelgallant

app-config-cli/package.json

@@ -43,6 +43,7 @@
     "@app-config/node": "^2.4.3",
     "@app-config/schema": "^2.4.3",
     "@app-config/utils": "^2.4.3",
+    "ajv": "7",
     "clipboardy": "2",
     "common-tags": "1",
     "execa": "5",