Github Actions CI build added (#174).

.github/workflows/ci.yml

+name: ci
+
+on: [push, pull_request]
+
+jobs:
+  build_linux:
+    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        compiler:
+          - gcc-10
+          - gcc-9
+          - gcc-8
+          - gcc-7
+          - clang-11
+          - clang-10
+          - clang-9
+          - clang-8
+          - clang-7
+    container:
+      image: "registry.gitlab.com/offa/docker-images/${{ matrix.compiler }}:stable"
+    name: "${{ matrix.compiler }}"
+    steps:
+      - uses: actions/checkout@master
+      - name: Build
+        run: script/ci_build.sh
+
+  build_conan:
+    runs-on: ubuntu-20.04
+    name: "Conan ${{ matrix.compiler }}"
+    steps:
+      - uses: actions/checkout@master
+      - name: Build
+        env:
+          CONAN_GCC_VERSIONS: 9
+        run: script/conan_build.sh

README.md

 # Scope Guard
 
+[![CI](https://github.com/offa/scope-guard/workflows/ci/badge.svg)](https://github.com/offa/scope-guard/actions)
 [![Build Status](https://travis-ci.org/offa/scope-guard.svg?branch=master)](https://travis-ci.org/offa/scope-guard)
 [![GitHub release](https://img.shields.io/github/release/offa/scope-guard.svg)](https://github.com/offa/scope-guard/releases)
 [![License](https://img.shields.io/badge/license-MIT-yellow.svg)](LICENSE)