Add github actions

Author: bamless

.github/workflows/build.yml

@@ -0,0 +1,21 @@
+name: Build
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-latest
+          - os: macos-latest
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@v4
+    - name: Build & Test
+      run: make examples test -j

README.md

@@ -1,5 +1,7 @@
 # extlib: c extended library
 
+[![Build](https://github.com/bamless/extlib/actions/workflows/build.yml/badge.svg)](https://github.com/bamless/extlib/actions/workflows/build.yml)
+
 extlib is a header-only library that implements common data structures and algorithms that are not
 provided by the c standard library.