build: name the quick-xml version ide-host uses in Cargo.lock (#1425)

#1176 brought in quick-xml 0.41 next to ide-host's 0.42, so ide-host's dependency in Cargo.lock must name its version; without it cargo rewrites the lock on every build and --locked builds fail.

Cargo.lock

@@ -4305,7 +4305,7 @@ dependencies = [
  "ide-workspace",
  "ignore",
  "parking_lot",
- "quick-xml",
+ "quick-xml 0.42.0",
  "regex-syntax",
  "reqwest",
  "rustix",