Clean dist/ before wheel build to prevent stale artifacts

Version bumps leave old wheels in dist/, causing the glob to
expand to multiple files and python-installer to fail.

pkg/PKGBUILD

@@ -4,7 +4,7 @@
 # Maintainer: Dominik Kressler
 
 pkgname=moonlock-git
-pkgver=0.0.0.r9.b365572
+pkgver=0.1.1.r0.g22f725e
 pkgrel=1
 pkgdesc="A secure Wayland lockscreen with GTK4, PAM and fingerprint support"
 arch=('any')
@@ -38,6 +38,7 @@ pkgver() {
 
 build() {
     cd "$srcdir/moonlock"
+    rm -rf dist/
     python -m build --wheel --no-isolation
 }