chore(deps): update dependency redis to v4

Author: renovate-bot

packages/opencensus-instrumentation-redis/package-lock.json

@@ -48,7 +48,7 @@
     "gts": "1.0.0",
     "mocha": "7.1.0",
     "nyc": "14.0.0",
-    "redis": "2.8.0",
+    "redis": "4.0.0",
     "rimraf": "3.0.0",
     "ts-node": "8.0.3",
     "typescript": "3.9.10"