feat: ensure all classes are marked final

Author: ramsey

src/Exception/RuntimeException.php

@@ -19,6 +19,6 @@
 /**
  * Exception thrown when an error occurs at runtime in the Twig extension
  */
-class RuntimeException extends RuntimeError
+final class RuntimeException extends RuntimeError
 {
 }

src/Exception/SyntaxException.php

@@ -19,6 +19,6 @@
 /**
  * Exception thrown when an error occurs when parsing the syntax of the Twig extension
  */
-class SyntaxException extends SyntaxError
+final class SyntaxException extends SyntaxError
 {
 }

src/Highlighter/HighlighterFactory.php

@@ -22,7 +22,7 @@
 /**
  * Factory to get a highlighter by name or by fully-qualified classname
  */
-class HighlighterFactory
+final class HighlighterFactory
 {
     /**
      * Returns an instance of a highlighter

src/Highlighter/HighlighterReference.php

@@ -14,6 +14,10 @@
 
 namespace Ramsey\Twig\CodeBlock\Highlighter;
 
+/**
+ * A reference to the highlighter class and its arguments, for use when compiling
+ * Twig templates
+ */
 final readonly class HighlighterReference
 {
     /**