Use ubuntu 20.04 which has GCC 8 atleast

.github/workflows/workflow.yaml

@@ -5,7 +5,7 @@ jobs:
   common:
     # TODO - Start using clang-tidy - requires a bit more setup though - http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html
     name: Linting & Formatting
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v2
@@ -19,7 +19,7 @@ jobs:
           ./third-party/run-clang-format/run-clang-format.py -r common decompiler game goalc test --color always
   build-linux:
     name: (Linux) Build & Test
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     defaults:
       run:
         shell: bash
@@ -50,7 +50,7 @@ jobs:
   build-windows:
     # Very good resource - https://cristianadam.eu/20191222/using-github-actions-with-c-plus-plus-and-cmake/
     name: (Windows) Build & Test
-    runs-on: windows-latest
+    runs-on: windows-2019
     defaults:
       run:
         shell: powershell