fix: plugins/proxy-backend/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-LODASHES-2434283
- https://snyk.io/vuln/SNYK-JS-ASYNC-2441827
- https://snyk.io/vuln/SNYK-JS-BRACES-6838727
- https://snyk.io/vuln/SNYK-JS-LODASHES-2434285
- https://snyk.io/vuln/SNYK-JS-LODASHES-2434284
- https://snyk.io/vuln/SNYK-JS-MICROMATCH-6838728
- https://snyk.io/vuln/SNYK-JS-LODASHES-2434289

plugins/proxy-backend/package.json

@@ -33,13 +33,13 @@
     "@types/express": "^4.17.6",
     "express": "^4.17.1",
     "express-promise-router": "^4.1.0",
-    "http-proxy-middleware": "^2.0.0",
+    "http-proxy-middleware": "^3.0.1",
     "morgan": "^1.10.0",
     "uuid": "^8.0.0",
-    "winston": "^3.2.1",
+    "winston": "^3.3.4",
     "yaml": "^1.9.2",
     "yn": "^4.0.0",
-    "yup": "^0.29.3"
+    "yup": "^0.32.10"
   },
   "devDependencies": {
     "@backstage/cli": "^0.7.2",