Pending RELEASE-NOTES for the upcoming release

This is work in progress and will change before the release goes public on 2025-07-16.

Changes:

Bugfixes:

• curl.h: make CURLSSLOPT_* symbols defined as longs
• docs/examples: add ftp-delete.c
• INSTALL.md: cygwin details and add source code link
• pytest: adapt for runs with openssl-1.1.1
• pytest: disable test_07_37 and test_07_36 with openssl's quic
• SCP/SFTP: avoid busy loop after EAGAIN
• system.h: remove some macros
• test1117: reduce write delays

Contributors:

Daniel Stenberg, John Haugabook, Stefan Eissing