Fix .SRCINFO containing pacman output

Redirect pacman install output to stderr so only makepkg
--printsrcinfo output ends up in .SRCINFO.

Author: bjarneo

.github/workflows/aur.yml

@@ -93,7 +93,7 @@ jobs:
           # Copy PKGBUILD and generate .SRCINFO
           cp ../PKGBUILD .
           docker run --rm -v "$PWD/PKGBUILD:/PKGBUILD:ro" archlinux:base bash -c \
-            'pacman -Sy --noconfirm pacman-contrib && cp /PKGBUILD /tmp/ && cd /tmp && chown nobody PKGBUILD && runuser -u nobody -- makepkg --printsrcinfo' > .SRCINFO
+            'pacman -Sy --noconfirm pacman-contrib >&2 && cp /PKGBUILD /tmp/ && cd /tmp && chown nobody PKGBUILD && runuser -u nobody -- makepkg --printsrcinfo' > .SRCINFO
 
           # Commit and push
           git add PKGBUILD .SRCINFO