Update links to gitlab

Cargo.toml

@@ -5,7 +5,7 @@ authors = ["ticki <ticki@users.noreply.github.com>"]
 
 # URLs and paths
 description = "An efficient alternative platform-agnostic allocator."
-repository = "https://github.com/redox-os/ralloc"
+repository = "https://gitlab.redox-os.org/redox-os/ralloc"
 readme = "README.md"
 
 # Metadata