migrate CI to github actions

Author: euclio

.github/workflows/ci.yaml

@@ -0,0 +1,39 @@
+on: push
+
+name: Continuous integration
+
+jobs:
+  ci:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        rust:
+          - stable
+          - beta
+          - nightly
+        features:
+          -
+          - --no-default-features --features json-rpc
+
+
+    steps:
+      - uses: actions/checkout@v1
+        with:
+          submodules: true
+
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          override: true
+
+      - uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: ${{ matrix.features }}
+
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: ${{ matrix.features }}

.travis.yml

@@ -1,6 +1,6 @@
 # vim-markdown-composer
 
-[![Build Status](https://travis-ci.org/euclio/vim-markdown-composer.svg)](https://travis-ci.org/euclio/vim-markdown-composer)
+![](https://github.com/euclio/vim-markdown-composer/workflows/Continuous%20integration/badge.svg)
 
 vim-markdown-composer is a plugin that adds asynchronous Markdown preview to
 [Neovim] and [Vim].