CI: add GitHub Action ubuntu build

.github/workflows/macos.yml

@@ -1,4 +1,4 @@
-name: MyCi_MacOS
+name: macOS CI
 
 on: [push]
 

.github/workflows/ubuntu.yml

@@ -0,0 +1,20 @@
+name: Ubuntu 20.04 CI
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-20.04
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Get build dept.
+      run: sudo apt install cmake qtbase5-dev libqt5svg5-dev qttools5-dev
+    - name: Build it
+      run: |
+        mkdir build
+        cd build
+        cmake ../
+        make
+        sudo cpack

README.md

@@ -3,6 +3,8 @@ Yet another image viewer.
 |CI|Build Status|
 |---|---|
 |Windows Build|[![Windows build status](https://ci.appveyor.com/api/projects/status/dbd8clww3cit6oa0/branch/master?svg=true)](https://ci.appveyor.com/project/BLumia/pineapplepictures/branch/master)|
+|macOS Build|![macOS CI](https://github.com/BLumia/PineapplePictures/workflows/macOS%20CI/badge.svg)|
+|Ubuntu 20.04 Build|![Ubuntu 20.04 CI](https://github.com/BLumia/PineapplePictures/workflows/Ubuntu%2020.04%20CI/badge.svg)|
 
 ![Pineapple Pictures - Main Window](https://repository-images.githubusercontent.com/211888654/21fb6300-269f-11ea-8e85-953e5d57da44)