Bump version for the 21.0.0 release

Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
12 jobs for 20.0.0 in 1 minute and 58 seconds
Status Name Job ID Coverage
  Docker Image
passed container-build #12351156

00:00:20

 
  Build
passed xserver-1.13 #12351159

00:00:22

passed xserver-1.14 #12351160

00:00:46

passed xserver-1.15 #12351161

00:00:21

passed xserver-1.16 #12351162

00:00:21

passed xserver-1.17 #12351163

00:00:23

passed xserver-1.18 #12351164

00:00:22

passed xserver-1.18-clang #12351165

00:00:24

passed xserver-1.19 #12351166

00:00:39

passed xserver-1.19-clang #12351167

00:00:26

passed xserver-1.20 #12351157

00:00:31

passed xserver-1.20-clang #12351158

00:00:42