fix(ci): install makepkg for repo-add utility scripts

repo-add from pacman-package-manager sources scripts from
/usr/share/makepkg/util/ which are shipped in the separate
makepkg package on Ubuntu.

.github/workflows/release.yml

@@ -251,7 +251,8 @@ jobs:
           sudo apt-get install -y --no-install-recommends \
             reprepro \
             createrepo-c \
-            pacman-package-manager
+            pacman-package-manager \
+            makepkg
 
       - name: GPG setup
         uses: kolaente/action-gpg@main