[Reg] build: CI: GitHub: Ubuntu: Remove 20.04 because of annoying GitHub deprecation practice.

git-svn-id: https://source.openmpt.org/svn/openmpt/trunk/OpenMPT@22952 56274372-70c3-4bfc-bfc3-4c3a0b034d27

Author: manxorist

.github/workflows/Ubuntu-Autotools.yml

@@ -15,7 +15,6 @@ jobs:
         include:
           - { version: '24.04' }
           - { version: '22.04' }
-          - { version: '20.04' }
 
     concurrency:
       group: ${{github.ref}}-${{github.workflow}}-${{matrix.version}}-autotools

.github/workflows/Ubuntu-Makefile.yml

@@ -19,9 +19,6 @@ jobs:
           - { version: '22.04', deps: sys   }
           - { version: '22.04', deps: local }
           - { version: '22.04', deps: small }
-          - { version: '20.04', deps: sys   }
-          - { version: '20.04', deps: local }
-          - { version: '20.04', deps: small }
 
     concurrency:
       group: ${{github.ref}}-${{github.workflow}}-${{matrix.version}}-${{matrix.deps}}