Use apt-get instead of apt

Author: jankapte

Dockerfile.ci

@@ -134,10 +134,12 @@ RUN mkdir -p /opt/protoc && \
 #
 # Ecosystem FVP License permits redistribution (refer to the relevant license available in the container).
 RUN set -o pipefail && \
-	apt update && \
-	apt install software-properties-common && \
 	add-apt-repository -y ppa:deadsnakes/ppa && \
-	apt install -y python3.9-dev && \
+	apt-get update && \
+	apt-get install --no-install-recommends -y \
+		software-properties-common \
+		python3.9-dev && \
+	rm -rf /var/lib/apt/lists/* && \
 	mkdir -p /opt/fvps && \
 	cd /opt/fvps && \
 	if [ "${HOSTTYPE}" = "x86_64" ]; then SUFFIX=""; else SUFFIX="_armv8l"; fi && \