OCI: Mitigate warnings emitted by Docker about new ENV syntax

  LegacyKeyValueFormat: "ENV key=value" should be used instead of
  legacy "ENV key value" format

Author: amotl

release/oci-runtime/Dockerfile

@@ -6,8 +6,8 @@
 
 FROM python:3.11-slim-bullseye
 
-ENV DEBIAN_FRONTEND noninteractive
-ENV TERM linux
+ENV DEBIAN_FRONTEND=noninteractive
+ENV TERM=linux
 
 # Install Git, it is needed for both `versioningit`, and MLflow.
 RUN rm -f /etc/apt/apt.conf.d/docker-clean; echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' > /etc/apt/apt.conf.d/keep-cache

release/oci-server/Dockerfile

@@ -6,8 +6,8 @@
 
 FROM python:3.11-slim-bullseye
 
-ENV DEBIAN_FRONTEND noninteractive
-ENV TERM linux
+ENV DEBIAN_FRONTEND=noninteractive
+ENV TERM=linux
 
 # Install Git, it is needed for both `versioningit`, and MLflow.
 RUN rm -f /etc/apt/apt.conf.d/docker-clean; echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' > /etc/apt/apt.conf.d/keep-cache