Fix Python warning of invalid escape in lyx_pot.py

Newer Python versions (e.g., Python 3.12.3) gave the following
warning:

  po/lyx_pot.py:607: SyntaxWarning: invalid escape sequence '\w'

An alternative fix would be to double the backslash, but that might
be less readable than this fix.

(cherry picked from commit 325f1429f83d7ce1d35404c3f99a31d19c0dbe45)

diff --git a/po/lyx_pot.py b/po/lyx_pot.py
index 665fdcddcfe35d6fd3806aafa5488f72e3b56294..76111bb71e456f650026438387b85e5581afbc61 100755 (executable)
--- a/po/lyx_pot.py
+++ b/po/lyx_pot.py
@@ -604,7 +604,7 @@ def encodings_l10n(input_files, output, base):
     output = io.open(output, 'w', encoding='utf_8', newline='\n')
     # assuming only one encodings file
     #                 Encoding utf8      utf8    "Unicode (utf8)" UTF-8    variable inputenc
-    reg = re.compile('Encoding [\w-]+\s+[\w-]+\s+"([\w \-\(\)\[\]\/^"]*)"\s+["\w-]+\s+(fixed|variable|variableunsafe)\s+\w+.*')
+    reg = re.compile(r'Encoding [\w-]+\s+[\w-]+\s+"([\w \-\(\)\[\]\/^"]*)"\s+["\w-]+\s+(fixed|variable|variableunsafe)\s+\w+.*')
     input = io.open(input_files[0], encoding='utf_8')
     for lineno, line in enumerate(input.readlines()):
         if not line.startswith('Encoding'):