Add a new stub test

Add a new stub test to show that some tags such as "rst2pdf" are not
automatically capitalised when converting a post's tags into hashtags.

web/modules/custom/blog/tests/src/Kernel/Action/ConvertPostToTweetTest.php

@@ -48,6 +48,10 @@ final class ConvertPostToTweetTest extends PostTestBase {
     $this->assertSame($expected, ($this->convertPostToTweet)($post));
   }
 
+  public function testSomeTagsAreNotAutomaticallyCapitalised(): void {
+    $this->markTestSkipped();
+  }
+
   protected function setUp() {
     parent::setUp();