deps: add suppaftp and parking_lot

suppaftp 12 is the FTP client behind the put FTP fallback transport:
the maintained continuation of rust-ftp (4.2M downloads, releases this
month), used with its default features only — a plain blocking FTP
stream, no TLS, no async. It brings just lazy-regex into the tree;
chrono is shared.

parking_lot replaces std sync mutex unwrapping in test code, per the
project rule.

Cargo.toml

@@ -35,6 +35,8 @@ gpgme = "0.11"
 serde_yaml = "0.9"
 lazy_static = "1.4.0"
 unicode-width = "0.2"
+parking_lot = "0.12"
+suppaftp = "12"
 
 [dev-dependencies]
 test-log = "0.2.19"