try

Author: naisila

circleci/images/exttester/Dockerfile

@@ -174,7 +174,7 @@ rm -rf /var/lib/apt/lists/*
 EOF
 
 RUN <<'EOF'
-apt purge -y \
+echo yes | apt purge -y \
     libpq5 \
 
 # infer the pgdgversion of postgres based on the $PG_VERSION