build(docker): override debian limitation for pip packages

New debian releases don't allow pip to install packages because they
might clash with debian packages.
Add a flag to override them when building docker images since they're
not going to break anything.

docker/postgres-kanister-tools/Dockerfile

@@ -11,8 +11,8 @@ ENV DEBIAN_FRONTEND noninteractive
 USER root
 
 RUN apt-get update && apt-get -y install curl python3 groff less jq python3-pip && \
-    pip3 install --upgrade pip && \
-    pip3 install --upgrade awscli && \
+    pip3 install --break-system-packages --upgrade pip && \
+    pip3 install --break-system-packages --upgrade awscli && \
     apt-get clean
 
 # Install restic to take backups

docker/postgresql/Dockerfile

@@ -9,9 +9,9 @@ RUN useradd -r --gid=0 --uid=1001 postgres
 RUN set -x \
 	&& apt-get update \
 	&& apt-get install -y curl groff lzop pv postgresql-client python3-pip daemontools \
-	&& pip3 install --upgrade pip \
+	&& pip3 install --break-system-packages --upgrade pip \
 	&& hash -r pip3 \
-	&& pip3 install wal-e[aws] \
-	&& pip3 install awscli
+	&& pip3 install --break-system-packages wal-e[aws] \
+	&& pip3 install --break-system-packages awscli
 
 USER postgres

examples/postgres-RDS/Dockerfile

@@ -5,8 +5,8 @@ ENV DEBIAN_FRONTEND noninteractive
 USER root
 
 RUN apt-get update && apt-get -y install curl python3-pip && \
-    pip3 install --upgrade pip && \
-    pip3 install --upgrade awscli && \
+    pip3 install --break-system-packages --upgrade pip && \
+    pip3 install --break-system-packages --upgrade awscli && \
     apt-get clean
 
 RUN curl https://raw.githubusercontent.com/kanisterio/kanister/master/scripts/get.sh | bash