build(deps): bump oven/bun from 1.1.4 to 1.1.20 in /.build

Bumps oven/bun from 1.1.4 to 1.1.20.

---
updated-dependencies:
- dependency-name: oven/bun
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

.build/Dockerfile

@@ -1,6 +1,6 @@
 # syntax = docker/dockerfile:1.4
 
-FROM --platform=$BUILDPLATFORM oven/bun:1.1.4 AS frontend-builder
+FROM --platform=$BUILDPLATFORM oven/bun:1.1.20 AS frontend-builder
 ARG DEBIAN_FRONTEND=noninteractive
 WORKDIR /build
 RUN apt-get -y update && apt-get install -y --no-install-recommends curl bash unzip