Upgrade squid 6.13 → 7.5 (6 stream EOL 2025-07)

[acortelyou]

Is your feature request related to a problem? Please describe.

squid (in SPECS/squid/squid.spec) is at 6.13 on the 6 release stream.

• 🔴 6 reached EOL 2025-07-10.
• Newer upstream releases: 1
• Latest upstream release: 7.5 (stream 7)
• Reference: https://endoflife.date/squid (checked 2026-04-22)

Describe the solution you'd like

Upgrade squid to 7.5.

Describe alternatives you've considered

• Stay on 6, assume security maintenance (support ended 2025-07-10).
• Retire the squid package.

Additional context

Newer upstream releases:

Stream	LTS?	Latest release	Status	Active support ends	EOL
7		7.5	🟢 supported	—	—