Update node build image to version 22.

The min version was bumped from 20 to 22 in
beancount/fava@365cd5d
which is included in fava release since v1.29. I'm surprised the node16
image was able to build Fava up until v1.28.

Dockerfile

@@ -1,7 +1,7 @@
 ARG BEANCOUNT_VERSION=2.3.6
 ARG FAVA_VERSION=v1.30
 
-ARG NODE_BUILD_IMAGE=16-bullseye
+ARG NODE_BUILD_IMAGE=22-bullseye
 FROM node:${NODE_BUILD_IMAGE} as node_build_env
 ARG FAVA_VERSION