ci: active Github Actions build

Author: JaCzekanski

main.yml renamed to .github/workflows/main.yml

@@ -7,28 +7,28 @@ jobs:
     name: "Linux Clang6"
     runs-on: ubuntu-18.04
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - run: ./.travis/linux/run-container.sh 6
 
   linux_clang8:
     name: "Linux Clang8"
     runs-on: ubuntu-18.04
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - run: ./.travis/linux/run-container.sh 8
 
   android:
     name: "Android"
     runs-on: ubuntu-18.04
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - run: ./.travis/android/run-container.sh
 
   macos:
     name: "macOS"
     runs-on: macOS-10.14
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - run: ./.travis/macos/install-dependencies.sh
     - run: ./.travis/macos/build.sh