update coverage

There were a couple of changes in
rust-vmm#76 that are not
yet tested. PR that covers that functionality is in review
here: rust-vmm#111.
Until that one is merged, the coverage needs to be decreased.

Signed-off-by: Laura Loghin <lauralg@amazon.com>

Author: lauralt

coverage_config_x86_64.json

@@ -1,5 +1,5 @@
 {
-  "coverage_score": 90.4,
+  "coverage_score": 83.6,
   "exclude_path": "crates/virtio-queue/src/mock.rs",
   "crate_features": "virtio-blk/backend-stdio"
 }