Replace travis-ci with Github CI

Travis CI is going the way of the dodo for open source,
as they introduced limitations which make it almost impossible to work with.
Github CI is an appealing alternative, free for open source,
expressive, and offering support for all three major platforms.

Author: Geod24

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+on: [ push, pull_request ]
+
+jobs:
+  main:
+    name: Run
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ ubuntu-latest ]
+        dc: [ dmd-latest, dmd-beta, ldc-latest ]
+
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: Prepare compiler
+        uses: dlang-community/setup-dlang@v1
+        with:
+          compiler: ${{ matrix.dc }}
+
+      - uses: actions/checkout@v2
+
+      - name: Test
+        if: matrix.dc != 'ldc-latest'
+        run: |
+          # Tests are neither random- nor parallelizable atm., so use a --single serial thread.
+          dub test --compiler=$DC  -- --single --trace
+
+      - name: Test with coverage
+        if: matrix.dc == 'ldc-latest'
+        env:
+          COVERAGE: true
+        run: |
+          # Mirrot the previous `run` step but with `--build=unittest-cov`
+          dub test --compiler=$DC --build=unittest-cov -- --single --trace
+
+      - name: Upload code coverage
+        if: matrix.dc == 'ldc-latest'
+        uses: codecov/codecov-action@v1

.travis.yml

@@ -449,6 +449,10 @@ void agentShutdownCheck(HTTPServerRequest req, HTTPServerResponse res)
 shared static this()
 {
     import std.process : environment;
+    // TODO: This should work on other compilers, but created a linker error on Github CI:
+    // /home/runner/work/dlang-bot/dlang-bot/source/dlangbot/app.d:460: error: undefined reference to '_D3etc5linux11memoryerror26registerMemoryErrorHandlerFZb'
+    // See https://github.com/dlang/dlang-bot/pull/263
+    version (DMD)
     version (linux)
     {
         // Only Glibc x86 / x86_64 supports this method, so check if defined