check HTML syntax on files starting with a BOM

src/PhpSpreadsheet/Reader/Html.php

@@ -147,10 +147,8 @@ class Html extends BaseReader
             return false;
         }
 
-        $beginning = $this->readBeginning();
-        if (preg_match(self::STARTS_WITH_BOM, $beginning)) {
-            return true;
-        }
+        $beginning = preg_replace(self::STARTS_WITH_BOM, '', $this->readBeginning()) ?? '';
+
         $startWithTag = self::startsWithTag($beginning);
         $containsTags = self::containsTags($beginning);
         $endsWithTag = self::endsWithTag($this->readEnding());

tests/PhpSpreadsheetTests/IOFactoryTest.php

@@ -102,6 +102,7 @@ class IOFactoryTest extends TestCase
             // Following not readable by Excel.
             //['samples/templates/Excel2003XMLTest.xml', 'Xml', Reader\Xml::class],
             ['samples/templates/46readHtml.html', 'Html', Reader\Html::class],
+            ['tests/data/Reader/CSV/encoding.utf8bom.csv', 'Csv', Reader\Csv::class],
         ];
     }