CI: Retire Cirrus CI as the service is shutting down

.cirrus.yml

@@ -1,25 +0,0 @@
-FreeBSD_task:
-  matrix:
-    env:
-      SSL: openssl
-      OPENSSL_ROOT_DIR: /usr/local
-    env:
-      SSL: openssl36
-      OPENSSL_ROOT_DIR: /usr/local
-    env:
-      # base openssl
-      SSL:
-  matrix:
-    freebsd_instance:
-      image_family: freebsd-14-3
-  prepare_script:
-    - pkg install -y pkgconf cmake git libsodium cpu_features $SSL
-    - git submodule update --init --recursive
-  configure_script:
-    - CMAKE_FLAGS="-DUSE_SYSTEM_CPU_FEATURES=1" CFLAGS="-I/usr/local/include/cpu_features" ./configure
-  build_script:
-    - make -j $(sysctl -n hw.ncpu || echo 4) -C build
-  test_script:
-    - ldd build/vpnserver
-    - .ci/memory-leak-test.sh
-    - .ci/vpntools-check.sh