Bump pkgrel so makepkg rebuilds instead of reusing the modelless archive

`makepkg -si` reported "A package has already been built, installing existing
package" and installed 0.7.0-1 — the archive from before the models were added,
so the install still had no model and the app still said so. The version had not
changed because the application had not changed; only what the package contains
did, which is precisely what pkgrel exists to signal.

Verified: 0.7.0-2 carries both models at /usr/share/darkroom/models/.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

packaging/PKGBUILD

@@ -5,7 +5,9 @@
 # on. Swap `source` for a tagged tarball when there is something to release.
 pkgname=darkroom
 pkgver=0.7.0
-pkgrel=1
+# 2: the package gained the face models (docs/faces.md §2.2a). Same version,
+# different contents, so makepkg must not reuse the 0.7.0-1 archive.
+pkgrel=2
 pkgdesc="Non-destructive RAW photo library and editor"
 arch=('x86_64')
 url="https://gitea.tourolle.paris/dtourolle/DarkRoom"