chore: Update changelog from release 26.7.0 (#1590)

Update CHANGELOG.md from release 26.7.0

Signed-off-by: Techassi <git@techassi.dev>

Author: Techassi

CHANGELOG.md

@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
 
+## [26.7.0] - 2026-07-21
+
+## [26.7.0-rc2] - 2026-07-20
+
+## [26.7.0-rc1] - 2026-07-16
+
 ### Added
 
 - ci: Generate SLSA build provenance for published image indexes and attest it in each registry ([#1559]).