Remove ubuntu-22.04 from matrix

ubuntu-22.04 only has gfortran version 12 and Julienne does not work with
gfortran 12, so remove ubuntu-22.04 from the gfortran matrix.

Author: bonachea

.github/workflows/build.yml

@@ -13,18 +13,12 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-13, macos-14, macos-15, macos-15-intel, ubuntu-22.04, ubuntu-24.04]
+        os: [macos-13, macos-14, macos-15, macos-15-intel, ubuntu-24.04]
         compiler: [ gfortran ]
         version: [ 13, 14, 15 ]
         extra_flags: [ -g -O3 ]
 
         exclude:
-          - os: ubuntu-22.04
-            version: 13 # no package available
-          - os: ubuntu-22.04
-            version: 14 # no package available
-          - os: ubuntu-22.04
-            version: 15 # no package available
           - os: ubuntu-24.04
             version: 15 # no package available