bucky: use source instead of git

BioArchLinux/bucky/lilac.yaml

@@ -2,10 +2,6 @@ build_prefix: extra-x86_64
 maintainers:
   - github: starsareintherose
     email: kuoi@bioarchlinux.org
-pre_build: |
-    vcs_update
-post_build: |
-    git_pkgbuild_commit()
 update_on:
   - source: cmd
     cmd: curl -sS https://pages.stat.wisc.edu/~ane/bucky/downloads.html | grep '<td>[0-9]\+' | sed 's/<td>//g' | awk '{print $1}' | head -n 1