Bump node from 20.6.1-slim to 20.8.0-slim in /mpcontribs-portal

Bumps node from 20.6.1-slim to 20.8.0-slim.

---
updated-dependencies:
- dependency-name: node
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

mpcontribs-portal/Dockerfile

@@ -1,6 +1,6 @@
 FROM materialsproject/devops:python-3.1010.12 as base
 RUN apt-get update && apt-get install -y --no-install-recommends libopenblas-dev && apt-get clean
-FROM node:20.6.1-slim as node
+FROM node:20.8.0-slim as node
 
 FROM node as webpack-deps
 RUN apt-get update && apt-get install -y --no-install-recommends \