tests/run.sh: Run tarpaulin with a single thread

This is to avoid frequent deadlocks on CI.

Signed-off-by: Anderson Toshiyuki Sasaki <[email protected]>

Author: ansasaki

tests/run.sh

@@ -47,4 +47,5 @@ cargo tarpaulin --verbose \
       --ignore-panics --ignore-tests \
       --out Html --out Json \
       --all-features \
-      --engine llvm
+      --engine llvm \
+      -- --test-threads=1