missing wd, ENV format to fix warning

Author: abe-winter

.github/workflows/test.yml

@@ -36,4 +36,5 @@ jobs:
           cmake --build build --target install
           cmake --install build
       - name: test
+        working-directory: build
         run: etc/docker/tests/run_test.sh

etc/docker/base-images/Dockerfile.debian.bullseye

@@ -1,6 +1,6 @@
 FROM debian:bullseye
 
-ENV HOME /root
+ENV HOME=/root
 ARG DEBIAN_FRONTEND=noninteractive
 
 RUN apt-get update