Update defaults for batch emitting rules

Author: Bardin08

src/X.Serilog.Sinks.Telegram/Configuration/BatchEmittingRulesConfiguration.cs

@@ -33,7 +33,7 @@ public TimeSpan RuleCheckPeriod
     /// <summary>
     /// Gets or initializes the batch processing rules to be applied.
     /// </summary>
-    public IImmutableList<IRule> BatchProcessingRules { get; init; } = null!;
+    public IImmutableList<IRule> BatchProcessingRules { get; init; } = [];
 
     /// <summary>
     /// Gets the execution hooks that are extracted from the batch processing rules.

src/X.Serilog.Sinks.Telegram/Configuration/TelegramSinkConfiguration.cs

@@ -90,7 +90,7 @@ public int BatchPostingLimit
     /// <summary>
     /// Gets or sets the configuration for rules on emitting batches.
     /// </summary>
-    public BatchEmittingRulesConfiguration BatchEmittingRulesConfiguration { get; set; } = null!;
+    public BatchEmittingRulesConfiguration BatchEmittingRulesConfiguration { get; set; } = new();
 
     /// <summary>
     /// Gets or sets the configuration for filtering logs.