Use GitHub Actions, test GNAT CE 2020

ref #178

Author: jklmnn

.github/workflows/ci.yml

@@ -0,0 +1,26 @@
+name: CI
+
+on: push
+
+jobs:
+    gnat_community_2019:
+        name: gnat-community-2019
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v1
+            - name: GNAT Community 2019
+              run: docker run -v $PWD:/gneiss componolit/ci:gnat-community-2019 /bin/sh -c "/gneiss/test/linux.sh"
+    gnat_community_2020:
+        name: gnat-community-2020
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v1
+            - name: GNAT Community 2020
+              run: docker run -v $PWD:/gneiss componolit/ci:gnat-community-2020 /bin/sh -c "/gneiss/test/linux.sh"
+    genode:
+        name: Genode
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v1
+            - name: Genode
+              run: docker run -v $PWD:/gneiss componolit/ci:genode /bin/sh -c "/gneiss/test/genode.sh"