Fix: Handle assignment on table hooks

Author: BeyondEvil

src/pytest_html/table.py

@@ -29,6 +29,9 @@ def append(self, html):
 
 
 class Cell(Table):
+    def __setitem__(self, key, value):
+        self.insert(key, value)
+
     def insert(self, index, html):
         # backwards-compat
         if not isinstance(html, str):