fix: update message for .Should().Contain() (#205)

Author: rsking

src/FluentAssertions.Analyzers/Tips/Collections/CollectionShouldContainItem.cs

@@ -14,7 +14,7 @@ public class CollectionShouldContainItemAnalyzer : CollectionAnalyzer
         public const string DiagnosticId = Constants.Tips.Collections.CollectionShouldContainItem;
         public const string Category = Constants.Tips.Category;
 
-        public const string Message = "Use .Should()Contain() instead.";
+        public const string Message = "Use .Should().Contain() instead.";
 
         protected override DiagnosticDescriptor Rule => new DiagnosticDescriptor(DiagnosticId, Title, Message, Category, DiagnosticSeverity.Info, true);