make CLI authentication case-insensitive

[dataders]

in #99, we found out that users assume that authentication: CLI can also be given as authentication: cli which is not the case.

@JCZuurmond... if you're interested 👀

Spitball idea, but maybe we add an .upper() to the this snippet below. something like:

if type_auth.upper() in AZURE_AUTH_FUNCTIONS.keys()

dbt-sqlserver/dbt/adapters/sqlserver/connections.py

Lines 281 to 288 in 0d529de

	if type_auth in AZURE_AUTH_FUNCTIONS.keys():
	# create token if it does not exist
	if cls.TOKEN is None:
	azure_auth_function = AZURE_AUTH_FUNCTIONS[type_auth]
	token = azure_auth_function(credentials)
	cls.TOKEN = convert_access_token_to_mswindows_byte_string(
	token
	)

[JCZuurmond]

@swanderz : That would indeed solve the problem for when authentication type is cli instead of CLI (or cLi for that matter). However it would not make the other authentication types case insensitive.

I have the urge to restructure some code first so that we can add (py)tests. It would make me more confident about changing code without breaking it.

However, if we prefer to do a quick fix first, then that is ok with me.

[dataders]

no urgency to make a hotfix, given that this issue is documented and easily fixed. more tests would be great -- thanks for offering. Happy to add any tests you write to CircleCI.