Fix escape sequence for Python 3.12

A backslash-character pair that is not a valid escape sequence now generates a
SyntaxWarning. It outputs to stderr which makes the tests to fail.

See python/cpython#98401 .

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1061803

data/scripts/import-opendict.py

@@ -104,7 +104,7 @@ def xml_workaround(self, s):
 
     def sanitize_word(self, word):
         word = word[:1] + word[1:].replace('-','').replace('^','')
-        m = re.match('^([^0-9]+)[0-9]*', word)
+        m = re.match(r'^([^0-9]+)[0-9]*', word)
         return m.group(1)
 
     def yaml_cache_find_yaml_doc(self, opendict_id, word, pos):

data/scripts/import-stdict.py

@@ -100,7 +100,7 @@ def xml_workaround(self, s):
 
     def sanitize_word(self, word):
         word = word[:1] + word[1:].replace('-','').replace('^','')
-        m = re.match('^([^0-9]+)[0-9]*', word)
+        m = re.match(r'^([^0-9]+)[0-9]*', word)
         return m.group(1)
 
     def yaml_cache_find_yaml_doc(self, stdict_id, word, pos):

tests/checkhunspellversion.py

@@ -19,7 +19,7 @@ def main():
     first_line = hunspell.stdout.readline().decode('UTF-8')
     hunspell.kill()
 
-    m = re.match('^.*Hunspell ([0-9\.]+).$', first_line)
+    m = re.match(r'^.*Hunspell ([0-9\.]+).$', first_line)
     numbers = [int(s) for s in m.group(1).split('.')]
     if len(numbers) >= 3:
         if check_version(numbers, [1, 6, 2]):