[fix] brand - partial revert of e82e37ce

In commit e82e37ce accidentally the brand file was touched / partial
revert::

  export GIT_URL='https://github.com/searxng/searxng'
  export GIT_BRANCH='master'

Related: https://github.com/searxng/searxng/pull/515



Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>