Remove CI support for FreeBSD

.github/workflows/amd64_freebsd_cmake.yml

@@ -1,22 +0,0 @@
-name: amd64 FreeBSD CMake
-
-on:
-  push:
-  pull_request:
-  schedule:
-    # min hours day(month) month day(week)
-    - cron: '0 0 7,22 * *'
-
-jobs:
-  # Only MacOS hosted runner provides virtualisation with vagrant/virtualbox installed.
-  # see: https://github.com/actions/virtual-environments/tree/main/images/macos
-  make:
-    runs-on: macos-latest
-    steps:
-    - uses: actions/checkout@v2
-    - name: vagrant version
-      run: Vagrant --version
-    - name: VirtualBox version
-      run: virtualbox -h
-    - name: Build
-      run: cd cmake/ci/vagrant/freebsd && vagrant up