[CI][C++] Upgrade Alpine Linux to 3.18 from 3.16

### Describe the enhancement requested

3.16 reached EOL on 2024-05-23 and 3.17 reached EOL on 2024-11-22.

3.18 will reach EOL on 2025-05-09.

See also: https://alpinelinux.org/releases/

### Component(s)

C++, Continuous Integration