Minor enhancements

Source/QuestPDF/Drawing/ImageCanvas.cs

@@ -20,6 +20,11 @@ namespace QuestPDF.Drawing
             Settings = settings;
         }
         
+        ~ImageCanvas()
+        {
+            Bitmap?.Dispose();
+        }
+        
         public override void BeginDocument()
         {
             

Source/QuestPDF/Drawing/SvgCanvas.cs

@@ -14,6 +14,11 @@ namespace QuestPDF.Drawing
         internal SkWriteStream WriteStream { get; set; }
         internal ICollection<string> Images { get; } = new List<string>();
         
+        ~SvgCanvas()
+        {
+            WriteStream?.Dispose();
+        }
+        
         public override void BeginDocument()
         {
             

Source/QuestPDF/Fluent/GenerateExtensions.cs

@@ -156,7 +156,7 @@ namespace QuestPDF.Fluent
         /// <summary>
         /// Generates the document as a series of SVG images and returns them as a collection of strings.
         /// </summary>
-        public static IEnumerable<string> GenerateSvg(this IDocument document)
+        public static ICollection<string> GenerateSvg(this IDocument document)
         {
             return DocumentGenerator.GenerateSvg(document);
         }