Security update for apache2 (moderate)

This update for apache2 fixes the following issues:

The following security vulnerabilities were fixed:

• CVE-2018-1333: Fixed a worker exhaustion that could have lead to a denial
  of service via specially crafted HTTP/2 requests (bsc#1101689).
• CVE-2018-8011: Fixed a null pointer dereference in mod_md, which could
  have lead to a denial of service via specially crafted HTTP requests
  (bsc#1101688). Note: We are currently not shipping this modules, since
  it is still considered experimental, but we might start to ship it with
  future releases.

This update was imported from the SUSE:SLE-15:Update update project.