github: switch from ubuntu-22.04 to ubuntu-latest

Given that ubuntu-latest was changed some time ago to use ubuntu-22.04
instead of ubuntu-20.04, there is no need to specify the fixed 22.04
version of ubuntu.

Link: https://github.blog/changelog/2022-11-09-github-actions-ubuntu-latest-workflows-will-use-ubuntu-22-04/

Author: ldv-alt

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
       run: git diff-index --check --cached 4b825dc642cb6eb9a060e54bf8d69288fbee4904
 
   gcc12-x86_64:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     env:
       CC: gcc-12
       TARGET: x86_64
@@ -81,7 +81,7 @@ jobs:
       run: ci/run-build-and-tests.sh
 
   clang14-x86_64:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     env:
       CC: clang-14
       TARGET: x86_64
@@ -95,7 +95,7 @@ jobs:
       run: ci/run-build-and-tests.sh
 
   clang13-x86_64:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     env:
       CC: clang-13
       TARGET: x86_64