Bump concat-stream from 1.4.10 to 1.4.11 in /tools/buildimage/lib/imgadm

Bumps [concat-stream](https://github.com/maxogden/concat-stream) from 1.4.10 to 1.4.11.
- [Release notes](https://github.com/maxogden/concat-stream/releases)
- [Commits](max-mapper/concat-stream@v1.4.10...v1.4.11)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tools/buildimage/lib/imgadm/package-lock.json

@@ -10,7 +10,7 @@
     "backoff": "2.5.0",
     "bunyan": "1.8.12",
     "cmdln": "3.2.1",
-    "concat-stream": "1.4.10",
+    "concat-stream": "1.4.11",
     "docker-registry-client": "3.2.10",
     "extsprintf": "1.2.0",
     "findit2": "2.2.3",