Gracefully handle trailing slash on folder path when importing from a db dump to mysql

[nekohayo]

$ ./kanboard-sqlite2mysql.sh ../kanboard_perf_test_mysql/ foo_kanboard-perso -h localhost -u foo_kb1 -p

# Create MySQL data dump from SQLite database
done
check db-mysql.sql
# Generate schema in the MySQL database using Kanboard
mv: cannot stat `../kanboard_perf_test_mysql//config.php': No such file or directory

This is because I had the trailing slash (from bash autocompletion) in the target folder in the command. Ideally the script should handle this automatically and realize that it shouldn't add another trailing slash if there already is one.