infra Travis: Remove travis-ci build test

We don't need to build test with travis-ci.
The build test is already being worked in the github-action.
In addition, travis-ci causes unnecessary failures because the recent request count is not properly counted.

.travis.yml

@@ -1,19 +0,0 @@
-sudo: false
-
-os:
-  - linux
-
-language:
-  - cpp
-
-services:
-  - docker
-
-before_install:
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then docker pull jsuya/thorvg-ci-setup; fi
-
-script:
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then echo FROM jsuya/thorvg-ci-setup > Dockerfile; fi
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then echo ADD . /root >> Dockerfile; fi
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then docker build -t withgit .; fi
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then docker run withgit /bin/sh -c "cd /root && TRAVIS=true meson -Dexamples=true -Dtools=svg2png builddir && ninja -C builddir install"; fi