fix(core): add @types/node-fetch to runtime dependency (aws-amplify#1…

…1560)

The isomorphic-unfetch dependency re-exports artifacts from node-fetch
package in its .d.ts file. However, the node-fetch package does not
contain any .d.ts file with itself. So the exported artifacts can not be
resolved by tsc. It's not an issue before possibly because the client-s3
contains transitive runtime dependency of @types/node-fetch. Since
it's removed now, we are encountered with this error.

Adding the dependency to runtime instead of dev or peer deps to prevent
brokage for customers

packages/core/package.json

@@ -69,6 +69,7 @@
 		"@aws-sdk/client-cloudwatch-logs": "3.6.1",
 		"@aws-sdk/types": "3.6.1",
 		"@aws-sdk/util-hex-encoding": "3.6.1",
+		"@types/node-fetch": "2.6.4",
 		"isomorphic-unfetch": "^3.0.0",
 		"react-native-url-polyfill": "^1.3.0",
 		"tslib": "^1.8.0",