chore: add github actions

.github/workflows/run-tests.yaml

@@ -0,0 +1,16 @@
+name: Run tests
+on:
+  push:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository code
+        uses: actions/checkout@v5
+
+      - name: Setup nim
+        uses: jiro4989/setup-nim-action@v2
+
+      - name: Run tests
+        run: nimble test