Run host-toolchain CI jobs on ubuntu-26.04

GitHub moves ubuntu-latest to Ubuntu 26.04 between 2026-10-19 and
2026-11-19 (actions/runner-images#14748). Run the jobs that use the
runner's own compilers and tools on ubuntu-26.04 now to find breakage
before the rollout. Container jobs are unaffected.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

.github/workflows/codeql-analysis.yml

@@ -21,7 +21,7 @@ permissions:
 jobs:
   CodeQL-Build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     permissions:
       security-events: write