cli: Add --test-threads=1 option to cargo test

The --test-threads=1 option is required to be able to run end-to-end tests.
Without this option, these tests will fail due to running concurrently.
Learn more at #214.

Author: NunoAlexandre

ci/run

@@ -61,9 +61,14 @@ RUST_LOG=error ./target/release/radicle-registry-node \
   --base-path /tmp/radicle-registry \
   &
 registry_node_pid=$!
+
 # We build tests in release mode so that we can reuse the artifacts
-# from 'cargo build'
-cargo test --workspace --release --color=always
+# from 'cargo build'.
+#
+# Note: the "--test-threads=1" option is required to be able to run
+# end-to-end tests. Without this option, these tests will fail
+# due to running concurrently. Learn more at https://github.com/radicle-dev/radicle-registry/issues/214.
+cargo test --workspace --release --color=always -- --test-threads=1
 kill "$registry_node_pid"
 
 echo "--- Copy artifacts"