add basic OpenSUSE workflow

.github/workflows/opensuse.yml

@@ -0,0 +1,24 @@
+name: OpenSUSE
+
+on: [push]
+
+jobs:
+  tumbletweed:
+      name: gcc
+      runs-on: ubuntu-latest
+      container:
+        image: opensuse/tumbleweed
+      steps:
+        - name: Install prerequisites
+          run: |
+            zypper refresh
+            zypper --non-interactive install libopenssl-devel cmake gcc gcc-c++ tar gzip git ncurses-devel zlib-devel readline-devel
+        - uses: actions/checkout@master
+          with:
+            submodules: true
+        - name: Build
+          run: |
+            ./configure
+            make -j $(nproc || sysctl -n hw.ncpu || echo 4) -C build
+            ldd build/vpnserver
+