ci: Update workflow ubuntu version to 22.04

Author: EdCaunt

.github/workflows/pytest-core-mpi.yml

@@ -17,7 +17,7 @@ on:
 jobs:
   test-mpi-basic:
     name: pytest-mpi
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         python-version: ['3.9', '3.11']

.github/workflows/pytest-core-nompi.yml

@@ -58,14 +58,14 @@ jobs:
 
         - name: pytest-ubuntu-py39-gcc7-omp
           python-version: '3.9'
-          os: ubuntu-20.04
+          os: ubuntu-22.04
           arch: "gcc-7"
           language: "openmp"
           sympy: "1.9"
 
         - name: pytest-ubuntu-py310-gcc10-noomp
           python-version: '3.10'
-          os: ubuntu-20.04
+          os: ubuntu-22.04
           arch: "gcc-10"
           language: "C"
           sympy: "1.11"
@@ -79,7 +79,7 @@ jobs:
 
         - name: pytest-ubuntu-py39-gcc9-omp
           python-version: '3.9'
-          os: ubuntu-20.04
+          os: ubuntu-22.04
           arch: "custom"
           language: "openmp"
           sympy: "1.10"