ci/debian: Allow to install packages only for docparse

Will be used in next commit.

Signed-off-by: Petr Vorel <pvorel@suse.cz>

ci/debian.sh

@@ -1,6 +1,6 @@
 #!/bin/sh -eux
 # SPDX-License-Identifier: GPL-2.0-or-later
-# Copyright (c) 2018-2021 Petr Vorel <pvorel@suse.cz>
+# Copyright (c) 2018-2024 Petr Vorel <pvorel@suse.cz>
 
 # workaround for missing oldstable-updates repository
 # W: Failed to fetch http://deb.debian.org/debian/dists/oldstable-updates/main/binary-amd64/Packages
@@ -13,6 +13,18 @@ export DEBIAN_FRONTEND="noninteractive"
 
 apt="apt install -y --no-install-recommends"
 
+# see .github/workflows/metadata.yml
+if [ -n "$PACKAGES_FOR_DOCPARSE_ONLY" ]; then
+	$apt \
+		asciidoctor \
+		autoconf \
+		automake \
+		gcc \
+		ruby-asciidoctor-pdf
+
+	return 0
+fi
+
 $apt \
 	acl-dev \
 	asciidoc \