.add_missing_columns() does not take case insensitivity into account

[simonw]

SQLite columns are case insensitive - but the .add_missing_columns() method doesn't know that. This means that it can crash if it identifies a column that is a case-insensitive duplicate of an existing column.

sqlite-utils/sqlite_utils/db.py

Lines 1974 to 1980 in 4cc82fd

	def add_missing_columns(self, records):
	needed_columns = suggest_column_types(records)
	current_columns = self.columns_dict
	for col_name, col_type in needed_columns.items():
	if col_name not in current_columns:
	self.add_column(col_name, col_type)
	return self