packaging: Move builds to Ubuntu 22.04

As Ubuntu 20.04 will reach its EOL in April.

Signed-off-by: Fabiano Fidêncio <fabiano@fidencio.org>

tools/packaging/static-build/initramfs/Dockerfile

@@ -1,7 +1,7 @@
 # Copyright (c) 2022 Intel Corporation
 #
 # SPDX-License-Identifier: Apache-2.0
-FROM ubuntu:20.04
+FROM ubuntu:22.04
 
 ARG DEBIAN_FRONTEND=noninteractive
 ARG cryptsetup_repo=${cryptsetup_repo}
@@ -12,10 +12,7 @@ ARG lvm2_version=${lvm2_version}
 SHELL ["/bin/bash", "-o", "pipefail", "-c"]
 
 ENV TZ=UTC
-RUN apt-get update &&\
-    apt-get --no-install-recommends install -y software-properties-common &&\
-    add-apt-repository ppa:git-core/ppa -y &&\
-    apt-get update && apt-get upgrade -y && \
+RUN apt-get update && apt-get upgrade -y && \
     apt-get --no-install-recommends install -y \
 	    apt-utils \
 	    asciidoctor \