Fix Dockerfile ENV format to use key=value syntax

Co-authored-by: cristiangreco <316923+cristiangreco@users.noreply.github.com>

Author: Copilot

Dockerfile

@@ -1,7 +1,7 @@
 FROM debian:bookworm-20250721-slim
 LABEL maintainer="cristian@regolo.cc"
 
-ENV DEBIAN_FRONTEND noninteractive
+ENV DEBIAN_FRONTEND=noninteractive
 
 COPY install.sh /install.sh
 RUN sh /install.sh && rm /install.sh