Move global flags to the start of regular expressions (#349)

* Revert "Move global flags to the start of regular expressions (fix for issue #348)"

This reverts commit 13b544b.

* Move global flags to the start of regular expressions

Fix regex replacements for models where global flags were put at the end
of the pattern strings. These patterns are invalid as of Python 3.11.

calamari_ocr/ocr/text_processing/text_regularizer.py

@@ -72,7 +72,7 @@ def default_text_regularizer_params(params=TextProcessorParams(), groups=["simpl
 
     def replacement(old, new, regex=False):
         r = params.replacements.add()
-        r.old = "(?u)" + old[:-4] if regex and old.endswith("(?u)") else old
+        r.old = old
         r.new = new
         r.regex = regex
 
@@ -343,6 +343,14 @@ class TextRegularizer(TextProcessor):
     def __init__(self, params=default_text_regularizer_params()):
         super().__init__()
         self.params = params
+        self._fix_regex_flags()
+
+    def _fix_regex_flags(self):
+        # Fix regex replacements for older models where global flags were put at the end
+        # of the pattern string. These patterns are invalid as of Python 3.11.
+        for replacement in self.params.replacements:
+            if replacement.regex and replacement.old.endswith("(?u)"):
+                replacement.old = "(?u)" + replacement.old[:-4]
 
     def _apply_single(self, txt):
         for replacement in self.params.replacements: