package.json: Reference PoC feature branch as dependency

Author: RandomByte

package.json

@@ -100,7 +100,7 @@
 	"dependencies": {
 		"@ui5/builder": "^2.0.0",
 		"@ui5/logger": "^2.0.0",
-		"@ui5/server": "^2.0.0",
+		"@ui5/server": "SAP/ui5-server#feature-proxy",
 		"ajv": "^6.12.0",
 		"ajv-errors": "^1.0.1",
 		"chalk": "^3.0.0",