Use string environment declarations in docker-compose.yml
Use string environment declarations in docker-compose.yml

For compatibility with podman-compose. Note that we do not intend to
support podman-compose in general, if there are other incompatibilities,
but this change is straightforward enough to be worthwhile.

thijsc/rust-rdkafka,fede1024/rust-rdkafka,fede1024/rust-rdkafka,thijsc/rust-rdkafka,fede1024/rust-rdkafka