github: enable tests

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>

.github/workflows/main.yml

@@ -0,0 +1,12 @@
+on:
+  push:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install sharness
+        run:
+          git clone --depth 1 https://github.com/felipec/sharness.git t/sharness
+      - run: SHARNESS_TEST_SRCDIR=t/sharness t/main.t