Add curl to the container for healthcheck purposes (#89)

Dockerfile

@@ -10,7 +10,7 @@ RUN go build -v -o mlmym
 FROM debian:bullseye-slim
 WORKDIR /app
 RUN set -x && apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y \
-    ca-certificates && \
+    ca-certificates curl && \
     rm -rf /var/lib/apt/lists/*
 COPY --from=builder /app/mlmym /app/mlmym
 COPY --from=builder /app/templates /app/templates