Update cmake.yml

Author: yatisht

.github/workflows/cmake.yml

@@ -10,20 +10,6 @@ env:
   BUILD_TYPE: Release
 
 jobs:  
-  ubuntu-20-04:
-    runs-on: ubuntu-20.04
-    steps:
-    - uses: actions/checkout@master
-    - name: install pre-reqs and build
-      run: sudo ./install/installUbuntu.sh
-    - name: test
-      run: |
-        ./build/usher --help
-        ./build/matUtils --help
-        mpirun -np 1 ./build/matOptimize --help
-        ./build/ripples --help
-        command -v mafft
-
   ubuntu-22-04:
     runs-on: ubuntu-22.04
     steps: