fix: pin node-fetch to 2.6.2 (bug)

see node-fetch/node-fetch#1300

Author: shazron

package.json

@@ -6,7 +6,7 @@
   "dependencies": {
     "express": "^4.17.1",
     "@adobe/aio-lib-core-logging": "1.1.0",
-    "node-fetch": "^2.6.0",
+    "node-fetch": "2.6.2",
     "mockttp": "^2.2.3",
     "syswide-cas": "^5.3.0"
   },