fix(slug): remove all Supplemental Symbols in slug

Fix the `slug` function to remove *all* emojis in the Supplemental
Symbols and Pictographs Unicode block.

I'm not sure why originally only a partial range was removed, but this
change seems to align with GitHub-flavored Markdown.

While this will effectively fix issue #5998, it does not address the
underlying problem where slugs were never designed for widget IDs.

Author: TomJGooding

src/textual/_slug.py

@@ -37,7 +37,7 @@
     r"\U0001F300-\U0001F5FF"
     r"\U0001F600-\U0001F64F"
     r"\U0001F680-\U0001F6FF"
-    r"\U0001f926-\U0001f937"
+    r"\U0001F900-\U0001f9FF"
     r"\u200D"
     r"\u2640-\u2642"
 )

tests/test_slug.py

@@ -25,6 +25,8 @@
         ("test🙂test", "testtest"),
         ("test🤷test", "testtest"),
         ("test🤷🏻‍♀️test", "testtest"),
+        ("test🤖test", "testtest"),
+        ("test🧠test", "testtest"),
     ],
 )
 def test_simple_slug(text: str, expected: str) -> None: