chore(deps): bump acadrust for block header owned-handle fix

Picks up the fix that keeps a block's owned-handle list in sync with the
entities actually written, so AutoCAD no longer drops model-space geometry from
OCS-saved files.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Cargo.lock

@@ -70,7 +70,7 @@ checksum = "366ffbaa4442f4684d91e2cd7c5ea7c4ed8add41959a31447066e279e432b618"
 [[package]]
 name = "acadrust"
 version = "0.3.4"
-source = "git+https://github.com/HakanSeven12/acadrust?branch=main#1b97dd3d52729ddf68ad6a542efab1eac3ebe9c3"
+source = "git+https://github.com/HakanSeven12/acadrust?branch=main#7b6bbf4a620540e917d6254b1c87076f76909973"
 dependencies = [
  "ahash",
  "anyhow",
@@ -3309,7 +3309,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b577e2d69827c4740cba2b52efaad1c4cc7c73042860b199710b3575c68438d"
 dependencies = [
  "bytecount",
- "memchr 2.8.1",
+ "memchr 1.0.2",
  "nom 8.0.0",
 ]