xtask: standalone, not workspace member

Author: dream-dasher

.cargo/config.toml

@@ -4,4 +4,5 @@
 # [Cargo Book: Configuration](https://doc.rust-lang.org/cargo/reference/config.html#env)
 
 [alias]
-xtask = "run --package xtask --"
+# xtask = "run --package xtask --"
+xtask = "run --manifest-path ./xtask/Cargo.toml --"