Fix CI build.sh step

Signed-off-by: Max Dymond <max.dymond@microsoft.com>

Author: Max Dymond

.devcontainer/Dockerfile.alpine

@@ -6,5 +6,3 @@ RUN apk update && \
     apk add bash musl-dev shadow && \
     # Add a user for floki using the shadow utils
     useradd -Um -s /bin/bash floki
-
-USER floki

floki.yaml

@@ -9,4 +9,6 @@ volumes:
     mount: /usr/local/cargo/registry
 
 forward_ssh_agent: true
-shell: bash
+shell:
+  outer: bash
+  inner: su floki