Parallel execution disabled to avoid random failures due to race condition.

Recyclable.CollectionsTests/xunit.runner.json

@@ -1,6 +1,6 @@
 {
 	"$schema": "https://xunit.net/schema/current/xunit.runner.schema.json",
 	"methodDisplay": "method",
-	"parallelizeTestCollections": true,
+	"parallelizeTestCollections": false,
 	"preEnumerateTheories": false
 }