Getting jira token from auth source breaks with some auth source backends

[vseguip]

Some custom emacs source backends return the secret as string and not functions which breaks the current jira-api--token function. The fix is to use auth built-in function auth-info-password which can retrieve the secret from either kind. E.g

(defun jira-api--token ()
    "Retrieve the token for current JIRA URL from config or auth-source."
    (if (and jira-token (not (string= "" jira-token)))
	jira-token
      (let* ((current-url (jira-api--get-current-url))
             (auth-host (replace-regexp-in-string "https://" "" current-url))
	     (auth-info (car (auth-source-search :host auth-host :require '(:secret)))))
	(when auth-info (auth-info-password auth-info)))))