Update GitLab CI to OpenBSD 6.6

Since OpenBSD 6.6 is the current OpenBSD release, replace OpenBSD 6.5
GitLab CI jobs with their up-to-date counterparts.

As CI jobs for OpenBSD 6.6 will be run by a generalized libvirt executor
rather than an OpenBSD-specific one, make the necessary tag and variable
adjustments as well.

.gitlab-ci.yml

@@ -60,7 +60,7 @@ stages:
 
 .openbsd-amd64: &openbsd_amd64
   tags:
-    - openbsd
+    - libvirt
     - amd64
 
 ### Docker Image Templates
@@ -1071,20 +1071,23 @@ unit:clang:freebsd12.0:amd64:
     - clang:freebsd12.0:amd64
   needs: ["clang:freebsd12.0:amd64"]
 
-# Jobs for Clang builds on OpenBSD 6.5 (amd64)
+# Jobs for Clang builds on OpenBSD 6.6 (amd64)
 
-clang:openbsd6.5:amd64:
+clang:openbsd6.6:amd64:
   variables:
     CC: clang
+    USER: gitlab-runner
   <<: *openbsd_amd64
   <<: *build_job
 
-system:clang:openbsd6.5:amd64:
+system:clang:openbsd6.6:amd64:
   <<: *openbsd_amd64
   <<: *system_test_job
+  variables:
+    USER: gitlab-runner
   dependencies:
-    - clang:openbsd6.5:amd64
-  needs: ["clang:openbsd6.5:amd64"]
+    - clang:openbsd6.6:amd64
+  needs: ["clang:openbsd6.6:amd64"]
   only:
     - schedules
     - tags

PLATFORMS

@@ -34,7 +34,7 @@ offer support on a "best effort" basis for some.
 
 Regularly tested platforms
 
-As of Dec 2019, BIND 9.15 is fully supported and regularly tested on the
+As of Feb 2020, BIND 9.15 is fully supported and regularly tested on the
 following systems:
 
   * Debian 9, 10
@@ -42,7 +42,7 @@ following systems:
   * Fedora 31
   * Red Hat Enterprise Linux / CentOS 7, 8
   * FreeBSD 11.3, 12.0
-  * OpenBSD 6.5
+  * OpenBSD 6.6
   * Alpine Linux
 
 The amd64, i386, armhf and arm64 CPU architectures are all fully

PLATFORMS.md

@@ -42,7 +42,7 @@ offer support on a "best effort" basis for some.
 
 ### Regularly tested platforms
 
-As of Dec 2019, BIND 9.15 is fully supported and regularly tested on the
+As of Feb 2020, BIND 9.15 is fully supported and regularly tested on the
 following systems:
 
 * Debian 9, 10
@@ -50,7 +50,7 @@ following systems:
 * Fedora 31
 * Red Hat Enterprise Linux / CentOS 7, 8
 * FreeBSD 11.3, 12.0
-* OpenBSD 6.5
+* OpenBSD 6.6
 * Alpine Linux
 
 The amd64, i386, armhf and arm64 CPU architectures are all fully supported.