fix(pkg): declare gtk4 build deps for GTK rust apps

moongreet/moonlock/moonset link against gtk4 headers at build time.
The CI workflow runs `makepkg -sfd` and only installs makedepends
explicitly — with gtk4 listed only in depends, the build container
had no cairo.pc / gtk4.pc and cairo-sys-rs failed to find the
system library. Add gtk4, gtk4-layer-shell, pkgconf (plus
gtk-session-lock + pam for moonlock) to makedepends.

This previously only worked because repeated `makepkg -s` runs
left the libs installed in the act_runner container filesystem.
Recreating the runner today exposed the latent gap.

moonlock-git/.SRCINFO

@@ -1,12 +1,17 @@
 pkgbase = moonlock-git
 	pkgdesc = A secure Wayland lockscreen with GTK4, PAM and fingerprint support
 	pkgver = 0.6.9.r1.g3f4448c
-	pkgrel = 1
+	pkgrel = 5
 	url = https://gitea.moonarch.de/nevaforget/moonlock
 	arch = x86_64
 	license = MIT
 	makedepends = git
 	makedepends = cargo
+	makedepends = gtk4
+	makedepends = gtk4-layer-shell
+	makedepends = gtk-session-lock
+	makedepends = pam
+	makedepends = pkgconf
 	depends = gtk4
 	depends = gtk4-layer-shell
 	depends = gtk-session-lock

moonlock-git/PKGBUILD

@@ -20,6 +20,11 @@ depends=(
 makedepends=(
     'git'
     'cargo'
+    'gtk4'
+    'gtk4-layer-shell'
+    'gtk-session-lock'
+    'pam'
+    'pkgconf'
 )
 optdepends=(
     'fprintd: fingerprint authentication support'