ci: so long, Travis!

https://blog.travis-ci.com/2020-11-02-travis-ci-new-billing

.travis.yml

-# SPDX-License-Identifier: GPL-3.0-or-later
-
-language: c
-os:
-    - osx
-osx_image: xcode10.2
-addons:
-    homebrew:
-        packages:
-            - cmocka
-            - luajit
-            - libuv
-            - lmdb
-            - meson
-            - nghttp2
-        update: true
-compiler:
-    - clang
-notifications:
-    email:
-        on_success: never
-        on_failure: never
-jobs:
-    fast_finish: true
-env:
-    global:
-        - KNOT_DNS_VERSION=3.0
-        - MALLOC_CHECK_=3
-        - MALLOC_PERTURB_=223
-before_script:
-    - git clone -b ${KNOT_DNS_VERSION} https://gitlab.nic.cz/knot/knot-dns.git
-    - cd knot-dns
-    - autoreconf -fi
-    - ./configure --disable-static --disable-fastparser --disable-documentation --disable-daemon --disable-utilities --with-lmdb=no
-    - make -j2 install
-    - cd ..
-script:
-    - meson build_darwin --default-library=static --buildtype=debugoptimized --prefix=${HOME}/.local/usr -Dc_args='-fno-omit-frame-pointer'
-    - ninja -C build_darwin -v install
-    - meson test -C build_darwin --suite unit
-    - ${HOME}/.local/usr/sbin/kresd -h
-    - ${HOME}/.local/usr/sbin/kresd -V
-    - echo "quit()" | ${HOME}/.local/usr/sbin/kresd -a 127.0.0.1@53535 .