Security update for apache2

Open Source Vulnerabilities openSUSE-SU-2021:0908-1

This update for apache2 fixes the following issues: - fixed CVE-2021-30641 [bsc#1187174]: MergeSlashes regression - fixed CVE-2021-31618 [bsc#1186924]: NULL pointer dereference on specially crafted HTTP/2 request - fixed CVE-2020-13950 [bsc#1187040]: mod_proxy NULL pointer dereference - fixed CVE-2020-35452 [bsc#1186922]: Single zero byte stack overflow in mod_auth_digest - fixed CVE-2021-26690 [bsc#1186923]: mod_session NULL pointer dereference in parser - fixed CVE-2021-26691 [bsc#1187017]: Heap overflow in mod_session