Remove CentOS 6 from GitLab CI

CentOS 6 will reach EoL on November 30th, 2020, i.e. before BIND 9.18
will be released.  Remove it from GitLab CI.
76 jobs for !3799 with ondrej/remove-distros-near-eol in 3 minutes and 39 seconds (queued for 5 seconds)
detached
Status Job ID Name Coverage
  Autoconf
canceled #1002598
amd64 linux
autoreconf

00:00:13

 
  Precheck
passed #1002600
amd64 linux
clang-format

00:00:19

passed #1002601
amd64 linux
coccinelle

00:03:39

passed #1002602
amd64 linux
danger

00:00:13

passed #1002599
amd64 linux
misc

00:00:18

 
  Build
skipped #1002616
amd64 linux
clang:asan
skipped #1002620
amd64 linux
clang:buster:amd64
skipped #1002623
amd64 libvirt
clang:freebsd11.4:amd64
skipped #1002624
amd64 libvirt
clang:freebsd12.1:amd64
skipped #1002625
amd64 libvirt
clang:openbsd6.7:amd64
skipped #1002618
amd64 linux
clang:tsan
skipped #1002603
amd64 linux
gcc:alpine3.12:amd64
skipped #1002615
amd64 linux
gcc:asan
skipped #1002607
amd64 linux
gcc:buster:amd64
skipped #1002604
amd64 linux
gcc:centos7:amd64
skipped #1002605
amd64 linux
gcc:centos8:amd64
skipped #1002614
amd64 linux
gcc:focal:amd64
skipped #1002619
amd64 linux
gcc:mutexatomics
skipped #1002609
amd64 linux
gcc:out-of-tree
skipped #1002608
amd64 linux
gcc:sid:amd64
skipped #1002610
arm64 linux
gcc:sid:arm64
skipped #1002611
i386 linux
gcc:sid:i386
skipped #1002621
amd64 linux
gcc:softhsm2.4
skipped #1002622
amd64 linux
gcc:softhsm2.6
skipped #1002606
amd64 linux
gcc:stretch:amd64
skipped #1002617
amd64 linux
gcc:tsan
skipped #1002612
amd64 linux
gcc:tumbleweed:amd64
skipped #1002613
amd64 linux
gcc:xenial:amd64
canceled #1002626
amd64 windows
msvc:windows:amd64

00:00:15

 
  Unit
skipped #1002639
amd64 linux
unit:clang:asan
skipped #1002643
amd64 linux
unit:clang:buster:amd64
skipped #1002646
amd64 libvirt
unit:clang:freebsd11.4:amd64
skipped #1002647
amd64 libvirt
unit:clang:freebsd12.1:amd64
skipped #1002641
amd64 linux allowed to fail
unit:clang:tsan
skipped #1002627
amd64 linux
unit:gcc:alpine3.12:amd64
skipped #1002638
amd64 linux
unit:gcc:asan
skipped #1002631
amd64 linux
unit:gcc:buster:amd64
skipped #1002628
amd64 linux
unit:gcc:centos7:amd64
skipped #1002629
amd64 linux
unit:gcc:centos8:amd64
skipped #1002637
amd64 linux
unit:gcc:focal:amd64
skipped #1002642
amd64 linux
unit:gcc:mutexatomics
skipped #1002632
amd64 linux
unit:gcc:sid:amd64
skipped #1002633
arm64 linux
unit:gcc:sid:arm64
skipped #1002634
i386 linux
unit:gcc:sid:i386
skipped #1002644
amd64 linux
unit:gcc:softhsm2.4
skipped #1002645
amd64 linux
unit:gcc:softhsm2.6
skipped #1002630
amd64 linux
unit:gcc:stretch:amd64
skipped #1002640
amd64 linux allowed to fail
unit:gcc:tsan
skipped #1002635
amd64 linux
unit:gcc:tumbleweed:amd64
skipped #1002636
amd64 linux
unit:gcc:xenial:amd64
 
  System
skipped #1002660
amd64 linux
system:clang:asan
skipped #1002664
amd64 linux
system:clang:buster:amd64
skipped #1002667
amd64 libvirt
system:clang:freebsd11.4:amd64
skipped #1002668
amd64 libvirt
system:clang:freebsd12.1:amd64
skipped #1002662
amd64 linux allowed to fail
system:clang:tsan
skipped #1002648
amd64 linux
system:gcc:alpine3.12:amd64
skipped #1002659
amd64 linux
system:gcc:asan
skipped #1002652
amd64 linux
system:gcc:buster:amd64
skipped #1002649
amd64 linux
system:gcc:centos7:amd64
skipped #1002650
amd64 linux
system:gcc:centos8:amd64
skipped #1002658
amd64 linux
system:gcc:focal:amd64
skipped #1002663
amd64 linux
system:gcc:mutexatomics
skipped #1002653
amd64 linux
system:gcc:sid:amd64
skipped #1002654
arm64 linux
system:gcc:sid:arm64
skipped #1002655
i386 linux
system:gcc:sid:i386
skipped #1002665
amd64 linux
system:gcc:softhsm2.4
skipped #1002666
amd64 linux
system:gcc:softhsm2.6
skipped #1002651
amd64 linux
system:gcc:stretch:amd64
skipped #1002661
amd64 linux allowed to fail
system:gcc:tsan
skipped #1002656
amd64 linux
system:gcc:tumbleweed:amd64
skipped #1002657
amd64 linux
system:gcc:xenial:amd64
 
  Docs
skipped #1002669
amd64 linux
docs
 
  Postcheck
skipped #1002673
amd64 linux
cppcheck
skipped #1002670
amd64 linux
flake8
skipped #1002671
amd64 linux
pylint
skipped #1002672
amd64 linux
scan-build