update recipes

recipes/wip/rustcloud/recipe.toml

-#TODO mio crate error (after cargo update -p libc redox_syscall)
+#TODO openssl error (after cargo update)
 [source]
 git = "https://github.com/cetra3/rustcloud"
 [build]

recipes/wip/rustic/recipe.toml

-#TODO redox_syscall crate error
+#TODO can't update the crates, patch the "fragile" crate version
 [source]
 git = "https://github.com/rustic-music-player/rustic"
 [build]

recipes/wip/rustlings/recipe.toml

 #TODO Not compiled or tested
 [source]
 git = "https://github.com/rust-lang/rustlings"
-rev = "9a743f80c57cc6bf27819589a8ddb5a5579ab1a4"
 [build]
 template = "cargo"