ci: migrate from Travis to GitHub Actions for Coveralls integration

.github/workflow/coveralls.yml

@@ -0,0 +1,43 @@
+name: Python CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        python-version: ["2.7", "3.3", "3.4", "3.5", "3.6", "3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+
+    steps:
+      - name: Check out the repository
+        uses: actions/checkout@v3
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: |
+          pip install nose
+          pip install mock
+          pip install coveralls
+          pip install responses
+
+      - name: Run tests
+        run: |
+          nosetests --with-coverage --cover-package=nta
+
+      - name: Upload coverage to Coveralls
+        if: success()
+        run: coveralls
+        env:
+          COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}