build(deps): bump jenkins/jenkins in /kubernetes/monitoring/jenkins

Bumps jenkins/jenkins from 2.476-alpine to 2.478-alpine.

---
updated-dependencies:
- dependency-name: jenkins/jenkins
  dependency-type: direct:production
...

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

kubernetes/monitoring/jenkins/Dockerfile

@@ -1,4 +1,4 @@
-FROM jenkins/jenkins:2.476-alpine
+FROM jenkins/jenkins:2.478-alpine
 ARG BUILD_DATE
 ARG VCS_REF