Updated Github workflows configuration (#154)

* Added script to install g++-7 for CI

* Added script to install g++-7 and clang-8 for CI

Author: glynos

.github/workflows/skyr-url-ci.yml

@@ -307,6 +307,33 @@ jobs:
             COMMAND chmod +x ${cmake_dir}/cmake
           )
 
+      - name: Install GCC 7
+        id: install_gcc_7
+        if: startsWith(matrix.config.os, 'ubuntu') && ( matrix.config.cxx == 'g++-7' )
+        shell: bash
+        working-directory: ${{ env.HOME }}
+        run: |
+          sudo apt-get update
+          sudo apt-get -y install g++-7
+
+      - name: Install GCC 8
+        id: install_gcc_8
+        if: startsWith(matrix.config.os, 'ubuntu') && ( matrix.config.cxx == 'g++-8' )
+        shell: bash
+        working-directory: ${{ env.HOME }}
+        run: |
+          sudo apt-get update
+          sudo apt-get -y install g++-8
+
+      - name: Install Clang 8
+        id: install_clang_8
+        if: startsWith(matrix.config.os, 'ubuntu') && ( matrix.config.cxx == 'clang++-8' )
+        shell: bash
+        working-directory: ${{ env.HOME }}
+        run: |
+          sudo apt-get update
+          sudo apt-get -y install clang-8
+
       - name: Install Clang 10
         id: install_clang_10
         if: startsWith(matrix.config.os, 'ubuntu') && ( matrix.config.cxx == 'clang++-10' )