replace travis with gha (disposable-email-domains#269)

* replace travis with gha

* install reqs

* write a message when check is ok

so it can be read easily in CI

.github/workflows/pr.yml

@@ -0,0 +1,17 @@
+name: validate blocklist entries
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  setup:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+      - run: pip install -r requirements.txt && python verify.py

verify.py

@@ -128,3 +128,5 @@ def check_for_intersection(filename_a, filename_b):
 
     # Check if any domains are in both the allowlist and blocklist
     check_for_intersection(allowlist, blocklist)
+
+    print("All domain entries seem valid.")