build: Bump gdbstub from 0.6.3 to 0.6.4

Bumps [gdbstub](https://github.com/daniel5151/gdbstub) from 0.6.3 to 0.6.4.
- [Release notes](https://github.com/daniel5151/gdbstub/releases)
- [Changelog](https://github.com/daniel5151/gdbstub/blob/master/CHANGELOG.md)
- [Commits](https://github.com/daniel5151/gdbstub/compare/0.6.3...0.6.4)

---
updated-dependencies:
- dependency-name: gdbstub
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.lock

@@ -382,9 +382,9 @@ checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
 [[package]]
 name = "gdbstub"
-version = "0.6.3"
+version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32c95766e0414f8bfc1d07055574c621b67739466d6ba516c4fef8e99d30d2e6"
+checksum = "ba4fddc6f9d12cbef29e395d9a6b48c128f513c8a2ded7048c97ed5c484e53e7"
 dependencies = [
  "bitflags",
  "cfg-if",

vmm/Cargo.toml

@@ -22,7 +22,7 @@ block_util = { path = "../block_util" }
 devices = { path = "../devices" }
 epoll = "4.3.1"
 event_monitor = { path = "../event_monitor" }
-gdbstub = { version = "0.6.3", optional = true }
+gdbstub = { version = "0.6.4", optional = true }
 gdbstub_arch = { version = "0.2.4", optional = true }
 hypervisor = { path = "../hypervisor" }
 libc = "0.2.139"