Get CI off of about-to-be-removed Ubuntu 20.04

.github/workflows/autotools-cmake.yml

@@ -50,10 +50,10 @@ jobs:
           - os: macos-14
             configure_args:
             cmake_args:
-          - os: ubuntu-20.04
+          - os: ubuntu-22.04
             configure_args:
             cmake_args:
-          - os: ubuntu-20.04
+          - os: ubuntu-22.04
             configure_args: --host=i686-w64-mingw32
             cmake_args: -DCMAKE_TOOLCHAIN_FILE=cmake/mingw-toolchain.cmake
     defaults:

.github/workflows/cmake-required-version.yml

@@ -44,7 +44,7 @@ permissions:
 jobs:
   checks:
     name: Ensure realistic minimum CMake version requirement
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683  # v4.2.2
 

.github/workflows/expat_config_h.yml

@@ -43,7 +43,7 @@ permissions:
 jobs:
   checks:
     name: Check expat_config.h.{in,cmake} for regressions
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683  # v4.2.2
     - name: Check expat_config.h.{in,cmake} for regressions

.github/workflows/linux.yml

@@ -82,7 +82,7 @@ jobs:
             FLAT_ENV: CC=i686-w64-mingw32-gcc CXX=i686-w64-mingw32-g++ LD=i686-w64-mingw32-ld QA_PROCESSOR=gcov CMAKE_ARGS="-DCMAKE_SYSTEM_NAME=Windows -DWIN32=ON -DMINGW=ON -DEXPAT_ATTR_INFO=ON"
           - MODE: qa-sh
             FLAT_ENV: CC=i686-w64-mingw32-gcc CXX=i686-w64-mingw32-g++ LD=i686-w64-mingw32-ld QA_PROCESSOR=gcov CMAKE_ARGS="-DCMAKE_SYSTEM_NAME=Windows -DWIN32=ON -DMINGW=ON -DEXPAT_ATTR_INFO=ON -DEXPAT_CHAR_TYPE=wchar_t"
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     env:
       CFLAGS: -g3 -pipe
     steps:

.github/workflows/valid-xml.yml

@@ -43,7 +43,7 @@ permissions:
 jobs:
   checks:
     name: Ensure well-formed and valid XML
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683  # v4.2.2