fluxbb: remove casing inconsistency in menu

Fixes: 98f20948 ("fluxbb: update the navbar url from bugs to gitlab")

roles/fluxbb/templates/config.php.j2

@@ -19,7 +19,7 @@ $arch_navbar = array('Home' => 'http://archlinux.org/',
                       'Packages' => 'http://archlinux.org/packages/',
                       'Forums' => 'https://bbs.archlinux.org/',
                       'Wiki' => 'https://wiki.archlinux.org/',
-                      'Gitlab' => 'https://gitlab.archlinux.org/archlinux',
+                      'GitLab' => 'https://gitlab.archlinux.org/archlinux',
                       'Security' => 'https://security.archlinux.org/',
                       'AUR' => 'https://aur.archlinux.org/',
                       'Download' => 'http://archlinux.org/download/');