feat: add log to journald feature

The systemd-journald is used in most major Linux distros that use systemd.
This enables logging using the systemd-journald native protocol, instead
of just writing to stderr.

Cargo.lock

@@ -1250,6 +1250,7 @@ dependencies = [
  "timeago",
  "tokio",
  "tracing",
+ "tracing-journald",
  "tracing-subscriber",
 ]
 
@@ -4514,6 +4515,17 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "tracing-journald"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc0b4143302cf1022dac868d521e36e8b27691f72c84b3311750d5188ebba657"
+dependencies = [
+ "libc",
+ "tracing-core",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "tracing-log"
 version = "0.2.0"