Update build.yml

Author: albertmena

.github/workflows/build.yml

@@ -23,7 +23,7 @@ jobs:
           - os: 'ubuntu-22.04'
             cuda: {version: '11.3.1', method: 'network'}
             compiler: {cc: gcc-9, cxx: g++-9, update-alternatives: True}
-          - os: 'ubuntu-22.04'
+          - os: 'ubuntu-20.04'
             cuda: {version: '10.2.89', method: 'local'}
             compiler: {cc: gcc-8, cxx: g++-8, update-alternatives: True}