installer: switch recipe to local fork (path-based source)

Use local/sources/installer/ as path source instead of git+patch.
The fork is synced to upstream 142b2d6. The ext4/GRUB patch will
be re-applied to the fork as a follow-up.

Author: vasilito <adminpupkin@gmail.com>

recipes/core/installer/recipe.toml

@@ -1,6 +1,5 @@
 [source]
-git = "https://gitlab.redox-os.org/redox-os/installer.git"
-patches = ["redox.patch"]
+path = "../../../local/sources/installer"
 
 [build]
 template = "cargo"