fix: backend/package.json & backend/package-lock.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-AXIOS-9403194

backend/package-lock.json

@@ -109,7 +109,7 @@
         "pino": "^8.16.2",
         "pkcs11js": "^2.1.6",
         "pkijs": "^3.2.4",
-        "posthog-node": "^3.6.2",
+        "posthog-node": "^5.0.0",
         "probot": "^13.3.8",
         "re2": "^1.21.4",
         "react": "19.1.0",
@@ -25011,15 +25011,12 @@
       "dev": true
     },
     "node_modules/posthog-node": {
-      "version": "3.6.2",
-      "resolved": "https://registry.npmjs.org/posthog-node/-/posthog-node-3.6.2.tgz",
-      "integrity": "sha512-tVIaShR3SxBx17AlAUS86jQTweKuJIFRedBB504fCz7YPnXJTYSrVcUHn5IINE2wu4jUQimQK6ihQr90Djrdrg==",
-      "dependencies": {
-        "axios": "^1.6.2",
-        "rusha": "^0.8.14"
-      },
+      "version": "5.0.0",
+      "resolved": "https://registry.npmjs.org/posthog-node/-/posthog-node-5.0.0.tgz",
+      "integrity": "sha512-gontigBt1pGHGXZme3+ojDdCYL66h/vvo+6KaQ6A51xqUOYgRvyzCLkS9Xv816jNBesRO8ouRjG428SDb2fFkg==",
+      "license": "MIT",
       "engines": {
-        "node": ">=15.0.0"
+        "node": ">=20"
       }
     },
     "node_modules/pprof-format": {
@@ -26909,11 +26906,6 @@
         "queue-microtask": "^1.2.2"
       }
     },
-    "node_modules/rusha": {
-      "version": "0.8.14",
-      "resolved": "https://registry.npmjs.org/rusha/-/rusha-0.8.14.tgz",
-      "integrity": "sha512-cLgakCUf6PedEu15t8kbsjnwIFFR2D4RfL+W3iWFJ4iac7z4B0ZI8fxy4R3J956kAI68HclCFGL8MPoUVC3qVA=="
-    },
     "node_modules/safe-array-concat": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/safe-array-concat/-/safe-array-concat-1.0.1.tgz",

backend/package.json

@@ -228,7 +228,7 @@
     "pino": "^8.16.2",
     "pkcs11js": "^2.1.6",
     "pkijs": "^3.2.4",
-    "posthog-node": "^3.6.2",
+    "posthog-node": "^5.0.0",
     "probot": "^13.3.8",
     "re2": "^1.21.4",
     "react": "19.1.0",