Add db.sqlite3-journal to Python.gitignore (#3063)

See also 15e56afe introduced this for Rails.gitignore.

Docs on Sqlite temporary files
https://www.sqlite.org/tempfiles.html#rollback_journals

Thanks @nickittynack (Nick Reynolds)

Python.gitignore

@@ -58,6 +58,7 @@ coverage.xml
 *.log
 local_settings.py
 db.sqlite3
+db.sqlite3-journal
 
 # Flask stuff:
 instance/