Update TypeScript Config to include only ./src

pika pack doesn't seem to know how to combine multiple globs from `include` in tsconfig into a single `index.d.ts` file, which causes types to be missing.

For now, exporting types for the ready to consume lambda handler is not strictly needed.

tsconfig.json

@@ -14,7 +14,7 @@
     "moduleResolution": "node",
     "sourceMap": true
   },
-  "include": ["./src/**/*", "./lambda/**/*"],
+  "include": ["./src/**/*"],
   "exclude": [
     "node_modules", "**/__MOCKS__/**/*", "**/__TEST__/**/*", "**/*.spec.ts"
   ]