Update dependency bl to v6

Author: renovate[bot]

package.json

@@ -127,7 +127,7 @@
     "braces": "^3.0.3",
     "lodash.template": "^4.5.0",
     "websocket-extensions": "^0.1.4",
-    "bl": "^3.0.1",
+    "bl": "^6.0.0",
     "dot-prop": "^4.2.1",
     "ini": "^1.3.7",
     "netmask": "^2.0.1",