Sync against taskchampion-sync-server (#3118)

This removes use of gnutls and the TLS implementation, which is no
longer needed (task synchronization is handled via Taskchampion, which
uses `reqwest`, which handles TLS via other Rust dependencies). This
incidentally removes the following config options:
 * `debug.tls`
 * `taskd.ca`
 * `taskd.certificate`
 * `taskd.ciphers`
 * `taskd.credentials`
 * `taskd.key`
 * `taskd.server`
 * `taskd.trust`

src/tc/rust/Cargo.lock

@@ -767,9 +767,9 @@ dependencies = [
 
 [[package]]
 name = "uuid"
-version = "1.3.4"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fa2982af2eec27de306107c027578ff7f423d65f7250e40ce0fea8f45248b81"
+checksum = "d023da39d1fde5a8a3fe1f3e01ca9632ada0a63e9797de55a879d6e2236277be"
 dependencies = [
  "getrandom",
  "serde",