Github updates ubuntu-latest to ubuntu 24.04 (actions/runner-images#10636).

This causes a lot of errors in CI:

https://github.com/phprus/zlib-ng/actions/runs/12568999002
https://github.com/phprus/zlib-ng/actions/runs/12568998935
https://github.com/phprus/zlib-ng/actions/runs/12568998934
https://github.com/phprus/zlib-ng/actions/runs/12568998931
https://github.com/phprus/zlib-ng/actions/runs/12568998928

Errors:

1. Old dependencies (e.g. clang-11). I suggest explicitly declaring the ubuntu version for such tests.
2. Problems due to ABI change in ubuntu 24.04 on ARM, MIPS, PPC: https://github.com/phprus/zlib-ng/actions/runs/12485475129/job/34844303420
3. Static analysis warnings/errors from the new version of clang: https://github.com/phprus/zlib-ng/actions/runs/12568998935/job/35037197233
4. Incompatibility in gcovr and new GCC (Unrecognized GCOV output).