fix(punctuation): correctly handle initial punctuation

Stripping and restoring initial punctuation didn't work correctly because the
string-splitting caused an additional empty string to be inserted in the text
list (because `".A".split(".")` => `["", "A"]`). Now, an initial empty string is
skipped and relevant test cases are added.

Fixes #3333

TTS/tts/utils/text/punctuation.py

@@ -106,11 +106,14 @@ class Punctuation:
         for idx, punc in enumerate(puncs):
             split = text.split(punc.punc)
             prefix, suffix = split[0], punc.punc.join(split[1:])
+            text = suffix
+            if prefix == "":
+                # We don't want to insert an empty string in case of initial punctuation
+                continue
             splitted_text.append(prefix)
             # if the text does not end with a punctuation, add it to the last item
             if idx == len(puncs) - 1 and len(suffix) > 0:
                 splitted_text.append(suffix)
-            text = suffix
         return splitted_text, puncs
 
     @classmethod

tests/text_tests/test_punctuation.py

@@ -13,6 +13,9 @@ class PunctuationTest(unittest.TestCase):
             ("This, is my text to be striped from text", "This is my text to be striped from text"),
             (".", ""),
             (" . ", ""),
+            ("!!! Attention !!!", "Attention"),
+            ("!!! Attention !!! This is just a ... test.", "Attention This is just a test"),
+            ("!!! Attention! This is just a ... test.", "Attention This is just a test"),
         ]
 
     def test_get_set_puncs(self):