Removed GH-Actions workflow for Ubuntu 20.04 LTS (EOL Apr 2025)

Author: Nightwalker-87

.github/workflows/c-cpp.yml

@@ -13,31 +13,6 @@ jobs:
       fail-fast: false
       matrix:
         config:
-          - name: Ubuntu20.04_x64 gcc9
-            os : ubuntu-20.04
-            cc : gcc-9
-            cxx : g++-9
-            packages: gcc-9 g++-9
-
-          - name: Ubuntu20.04_x64 gcc10
-            os : ubuntu-20.04
-            cc : gcc-10
-            cxx : g++-10
-            packages: gcc-10 g++-10
-
-          - name: Ubuntu20.04_x64 clang10
-            os : ubuntu-20.04
-            cc : clang-10
-            cxx : clang++-10
-            packages: gcc-9 g++-9 clang-10
-
-          - name: Ubuntu20.04_x64 clang12
-            os : ubuntu-20.04
-            cc : clang-12
-            cxx : clang++-12
-            packages: gcc-10 g++-10 clang-12
-
-
 
           - name: Ubuntu22.04_x64 gcc10
             os: ubuntu-22.04