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