fix(package.json): use --sign option in release script

The release script in package.json has been updated to use the --sign
option with the nlx bumpp command. This ensures that the release is
signed before it is published to npm.

Author: ryoppippi

package.json

@@ -13,7 +13,7 @@
 		"lint": "eslint --cache .",
 		"format": "nr lint --fix",
 		"typecheck": "tsc --noEmit",
-		"release": "nr typecheck && nr test run && nr build && nlx bumpp -s && npm publish"
+		"release": "nr typecheck && nr test run && nr build && nlx bumpp --sign && npm publish"
 	},
 	"dependencies": {
 		"await-to-js": "^3.0.0",