fix: Update superagent-proxy dependency to v3 (#4779)

Author: neurally

packages/@ionic/cli/package.json

@@ -63,7 +63,7 @@
     "ssh-config": "^1.1.1",
     "stream-combiner2": "^1.1.1",
     "superagent": "^5.2.1",
-    "superagent-proxy": "^2.0.0",
+    "superagent-proxy": "^3.0.0",
     "tar": "^6.0.1",
     "tslib": "^2.0.1"
   },
@@ -79,7 +79,7 @@
     "@types/semver": "^7.1.0",
     "@types/split2": "^2.1.6",
     "@types/superagent": "^4.1.3",
-    "@types/superagent-proxy": "^2.0.0",
+    "@types/superagent-proxy": "^3.0.0",
     "@types/tar": "^4.0.0",
     "jest": "^26.4.2",
     "jest-cli": "^26.0.1",