fix(auth): allows matching of mixed-case usernames

Allow inserting the lowercase version of the Gitlab username, since it's accepted by the Gitlab API

Author: GFWagnitz

src/gitlab.ts

@@ -97,7 +97,7 @@ export default class VerdaccioGitLab implements VerdaccioGitLabPlugin {
 
     GitlabAPI.Users.current()
       .then(response => {
-        if (user !== response.username) {
+        if (user !== response.username.toLowerCase()) {
           return cb(getUnauthorized('wrong gitlab username'));
         }