squid: Update to 6.13

squid: Update to 6.13

For details see:
https://github.com/squid-cache/squid/releases/tag/SQUID_6_13

"Changes in squid-6.13 (31 Jan 2025):

- Bug 5352: Do not get stuck when RESPMOD is slower than read(2)
- Bug 5405: Large uploads fill request buffer and die
- Bug 5093: List http_port params that https_port/ftp_port lack
- Bug 5311: clarify configuration byte units
- Bug 5091: document that changes to workers require restart
- Bug 5481: Fix GCC v14 build [-Wmaybe-uninitialized]
- Nil request dereference in ACLExtUser and SourceDomainCheck ACLs
- Fix GCC v14 [-Wanalyzer-null-dereference] warnings in Kerberos
- Clarify --enable-ecap failure on missing shared library support
- Fix syntax error in configure.ac
- Remove GNU'ism in release notes Makefile
- Annotate PoolMalloc memory in valgrind builds
- Fix systemd startup sequence to require active Local Filesystem
- Display Linux variant at ./configure time
- Refactor peerRefreshDNS() to clarify its (void*)1 logic
- Portability: remove explicit check for libdl
- ext_time_quota_acl: remove -l option
- ... and some documentation updates
- ... and some CI updates"

Signed-off-by: Matthias Fischer <matthias.fischer@ipfire.org>