Don't escape non-ASCII characters in CSV data

By default, 'json.dumps' escapes escapes non-ASCII characters, which is
undesirable for CSV data containing Unicode characters. This commit
causes all characters to be output as-is.

Addresses: #100

tools/csv-convert.py

@@ -1,26 +1,29 @@
 #! /usr/bin/python3
 
-# SMS Import / Export: a simple Android app for importing and exporting SMS messages from and to JSON files.
-# Copyright (c) 2023 Thomas More
+# SMS Import / Export: a simple Android app for importing and exporting SMS and
+# MMS messages, call logs, and contacts, from and to JSON / NDJSON files.
+#
+# Copyright (c) 2023, 2025 Thomas More
 #
 # This file is part of SMS Import / Export.
 #
 # SMS Import / Export is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
+# it under the terms of the GNU General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option) any
+# later version.
 #
-# SMS Import / Export is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-# GNU General Public License for more details.
+# SMS Import / Export is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+# details.
 #
-# You should have received a copy of the GNU General Public License
-# along with SMS Import / Export.  If not, see <https://www.gnu.org/licenses/>.
+# You should have received a copy of the GNU General Public License along with
+# SMS Import / Export.  If not, see <https://www.gnu.org/licenses/>.
 
 # Written for https://github.com/tmo1/sms-ie/issues/100
 
 import csv
 import json
 
-print(json.dumps(list(csv.DictReader(open(0, newline=''))), indent=2))
+print(json.dumps(list(csv.DictReader(open(0, newline=''))), indent=2, ensure_ascii=False))
+