Bump node from 22.22.3-slim to 26.5.0-slim in /.devcontainer

Bumps node from 22.22.3-slim to 26.5.0-slim.

---
updated-dependencies:
- dependency-name: node
  dependency-version: 26.5.0-slim
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.devcontainer/Dockerfile

@@ -1,7 +1,7 @@
 # Same version of nodejs as that used for
 # - vscode itself https://github.com/Microsoft/vscode/wiki/How-to-Contribute#prerequisites
 # - CI tests .github/workflows/build.yml
-FROM node:22.22.3-slim
+FROM node:26.5.0-slim
 
 # Packages
 # Includes fix for "debconf: delaying package configuration, since apt-utils is not installed"