Bump OS to bullseye and try a github CI docker build

.github/workflows/build.yml

@@ -0,0 +1,19 @@
+name: Build Canute UI book indexer
+on:
+  push:
+    branches:
+      - main
+      - 285-rust-cross-compilation
+  pull_request:
+    branches:
+      - main
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Check out code
+      uses: actions/checkout@v3
+    - name: Build docker images
+      run: docker build -t bristol-braille/bookindex:latest < Dockerfile
+    - name: Run tests
+      run: docker run -t -e "HOME=/work" -w /work -v "$PWD:/work" bristol-braille/bookindex:latest

Dockerfile

@@ -1,6 +1,6 @@
 # Based on https://github.com/mdirkse/rust_armv6
-# We use buster to match glibc versions with raspios old stable
-FROM rust:slim-buster
+# We use bullseye to match glibc versions with raspios old stable
+FROM --platform=linux/amd64 rust:slim-bullseye
 
 # Prevent any error messages about there not being a terminal
 ENV DEBIAN_FRONTEND noninteractive