Add Github Actions test workflow (parcel-bundler#57)

Author: devongovett

.github/workflows/test.yml

@@ -0,0 +1,11 @@
+name: test
+on:
+  push:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: Swatinem/rust-cache@v1
+      - run: cargo test