Run the testsuite on musl as well in the CI

.github/workflows/build-and-test.yml

@@ -7,7 +7,7 @@ on:
     - cron: '0 2 * * *'
 
 jobs:
-  build:
+  build-ubuntu-gcc:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
@@ -19,3 +19,13 @@ jobs:
       - uses: actions/checkout@v2
       - name: Build
         run: CC=clang CXX=clang++ make test
+  build-musl:
+    runs-on: ubuntu-latest
+    container:
+      image: alpine:latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install dependencies
+        run: apk add build-base python3
+      - name: Build
+        run: make test