printer: drop dependency on serde_derive

As suggested by @epage[1].

Ad hoc timings on my i7-12900K:

    before cargo build: 4.91s
    before cargo build release: 8.05s
    after cargo build: 4.69s
    after cargo build release: 7.83s

... pretty underwhelming if you ask me. Ah well. And on my M2 mac mini:

    before cargo build: 6.18s
    before cargo build release: 14.50s
    after cargo build: 5.52s
    after cargo build release: 13.44s

Still kind of underwhelming, but definitely better. It shaves a full
second off of compile times in release mode. I went back to my
i7-12900K, but passed `-j1` to `cargo build` to force single threaded
mode:

    before cargo build: 19.44s
    before cargo build release: 50.64s
    after cargo build: 16.76s
    after cargo build release: 48.00s

Which seems pretty consistent with the modest improvements above.

Looking at `cargo build --timings`, the beefiest chunk of time is spent
in compiling `regex-automata`, by far. This is fine because it's core
functionality. I wish a fast general purpose regex engine with its
internals exposed as a separately versioned library didn't require so
much code... Blech.

[1]: https://old.reddit.com/r/rust/comments/17rd8ww/faster_compilation_with_the_parallel_frontend_in/k8igjlg/

crates/printer/src/util.rs

@@ -8,9 +8,6 @@ use {
     },
 };
 
-#[cfg(feature = "serde")]
-use serde::{Serialize, Serializer};
-
 use crate::{hyperlink::HyperlinkPath, MAX_LOOK_AHEAD};
 
 /// A type for handling replacements while amortizing allocation.
@@ -385,11 +382,14 @@ impl NiceDuration {
 }
 
 #[cfg(feature = "serde")]
-impl Serialize for NiceDuration {
-    fn serialize<S: Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> {
+impl serde::Serialize for NiceDuration {
+    fn serialize<S: serde::Serializer>(
+        &self,
+        ser: S,
+    ) -> Result<S::Ok, S::Error> {
         use serde::ser::SerializeStruct;
 
-        let mut state = ser.serialize_struct("Duration", 2)?;
+        let mut state = ser.serialize_struct("Duration", 3)?;
         state.serialize_field("secs", &self.0.as_secs())?;
         state.serialize_field("nanos", &self.0.subsec_nanos())?;
         state.serialize_field("human", &format!("{}", self))?;