Allow the verify attribute to be bool or string

[waza-ari]

Both the KeycloakOpenID class as well as the KeycloakAdmin class (and subsequently also the ConnectionManager and KeycloakOpenIDConnection support a verify parameter which defines whether the SSL certificate should be checked. Currently, this is specified as being a boolean value.

That parameter is then subsequently passed to requests Session methods like get and put. According to the requests API description, this verify parameter actually accepts a boolean value or a string, in which case the value must be a path to a custom CA file used for certificate validation.

Passing a string works already today as the parameter is not validated and passed straight to the requests methods. I suggest updating the documentation and make clear that both a boolean value or a string can be passed.

This discussion came up during a MR on my own library making use of yours. See the following discussion for more details.