OPTIONS key type for DBConfig is potentially incorrect

[kezabelle]

2.0.0 introduces DBConfig as a TypedDict, specified as:

class DBConfig(TypedDict, total=False):
...
    OPTIONS: Optional[Dict[str, Any]]

As far as I can tell from a cursory reading of parse, it cannot be Optional (None) - options is always at least an empty directory ({}), but it can be NotRequired as a key (which is AFAIK already handled by the class being total=False) because if it is empty it just won't be set.

This came up for me because I have some code which does:

if "OPTIONS" in parsed_db_config:
    parsed_db_config["OPTIONS"].update(...some_stuff)

which gets raised as an error:

error: Item "None" of "Optional[Dict[str, Any]]" has no attribute "update"  [union-attr]

Here's the totality of options being used and then potentially bound to the OPTIONS key:

dj-database-url/dj_database_url/__init__.py

Lines 159 to 182 in 9b0f325

	options: Dict[str, Any] = {}
	for key, values in query.items():
	if spliturl.scheme == "mysql" and key == "ssl-ca":
	options["ssl"] = {"ca": values[-1]}
	continue
	options[key] = values[-1]
	if ssl_require:
	options["sslmode"] = "require"
	# Support for Postgres Schema URLs
	if "currentSchema" in options and engine in (
	"django.contrib.gis.db.backends.postgis",
	"django.db.backends.postgresql_psycopg2",
	"django.db.backends.postgresql",
	"django_redshift_backend",
	"timescale.db.backends.postgresql",
	"timescale.db.backends.postgis",
	):
	options["options"] = "-c search_path={0}".format(options.pop("currentSchema"))
	if options:
	parsed_config["OPTIONS"] = options

[palfrey]

#232 will fix this