Remove .travis.yml

This project now uses Github CI and travis CI configuration
is no longer used.

Fixes #630
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 9b2e077..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,87 +0,0 @@
-language: c
-os: linux
-dist: focal
-
-addons:
-  apt:
-    packages:
-      - ninja-build
-      - python3
-      - python3-pip
-
-before_script:
-  - curl -L https://www.nasm.us/pub/nasm/releasebuilds/2.15.05/nasm-2.15.05.tar.gz | tar xvz
-  - cd nasm-2.15.05
-  - ./configure && make -j2 && sudo make install
-  - nasm --version
-  - pip3 --disable-pip-version-check install setuptools
-  - pip3 --disable-pip-version-check install meson
-  - curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
-  - source $HOME/.cargo/env
-  - cd $TRAVIS_BUILD_DIR/ext
-  - export MAKEFLAGS=-j$(nproc)
-  - bash aom.cmd
-  - bash dav1d.cmd
-  - bash libgav1.cmd
-  - bash rav1e.cmd
-  - bash svt.cmd
-  - bash libyuv.cmd
-  - bash libsharpyuv.cmd
-  - cd ..
-  - mkdir build
-  - cd build
-script:
-  - cmake -G Ninja -DCMAKE_BUILD_TYPE=$config -DBUILD_SHARED_LIBS=OFF -DAVIF_CODEC_AOM=ON -DAVIF_LOCAL_AOM=ON -DAVIF_CODEC_DAV1D=ON -DAVIF_LOCAL_DAV1D=ON -DAVIF_CODEC_RAV1E=ON -DAVIF_LOCAL_RAV1E=ON -DAVIF_CODEC_LIBGAV1=ON -DAVIF_LOCAL_LIBGAV1=ON -DAVIF_CODEC_SVT=ON -DAVIF_LOCAL_SVT=ON -DAVIF_LOCAL_LIBYUV=ON -DAVIF_LOCAL_LIBSHARPYUV=ON -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON -DAVIF_BUILD_TESTS=ON ..
-  - ninja
-
-matrix:
-  include:
-  - name: "GCC Debug"
-    compiler: gcc
-    config: Debug
-  - name: "GCC Release"
-    compiler: gcc
-    config: Release
-  - name: "Clang Debug"
-    compiler: clang
-    config: Debug
-  - name: "Clang Debug (aom decode only)"
-    compiler: clang
-    config: Debug
-    script:
-      - cmake -G Ninja -DCMAKE_BUILD_TYPE=$config -DBUILD_SHARED_LIBS=OFF -DAVIF_CODEC_AOM=ON -DAVIF_LOCAL_AOM=ON -DAVIF_CODEC_AOM_ENCODE=0 -DAVIF_BUILD_APPS=ON ..
-      - ninja
-  - name: "Clang Debug (aom encode only)"
-    compiler: clang
-    config: Debug
-    script:
-      - cmake -G Ninja -DCMAKE_BUILD_TYPE=$config -DBUILD_SHARED_LIBS=OFF -DAVIF_CODEC_AOM=ON -DAVIF_LOCAL_AOM=ON -DAVIF_CODEC_AOM_DECODE=0 -DAVIF_BUILD_APPS=ON ..
-      - ninja
-  - name: "Clang Release"
-    compiler: clang
-    config: Release
-  - &freebsd_common
-    name: "Clang 10 + system libraries"
-    os: freebsd
-    compiler: clang
-    before_install:
-      - | # FreeBSD 12.2 has Clang 10 but TravisCI uses FreeBSD 12.1
-        if [[ $(${CC:-clang} --version) =~ 8.0 ]]; then
-          export CC=clang10 CXX=clang++10
-          sudo pkg install -y llvm10
-        fi
-    before_script:
-      - sudo pkg install -y aom dav1d libgav1 librav1e svt-av1 ninja
-      - $WRAPPER cmake -B build -G Ninja -DAVIF_{CODEC_{AOM,DAV1D,LIBGAV1,RAV1E,SVT},BUILD_{APPS,TESTS}}=ON
-    script:
-      - $WRAPPER cmake --build build
-  - <<: *freebsd_common
-    name: "GCC 10 + system libraries"
-    compiler: gcc
-    before_install:
-      - sudo pkg upgrade -y gcc10-devel
-  - <<: *freebsd_common
-    name: "Clang Static Analyzer"
-    env: WRAPPER="scan-build11 --status-bugs"
-    before_install:
-      - sudo pkg install -y llvm11