chore: release 3.26.0-0codspeed4

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: adriencaccia

debian/changelog

@@ -1,3 +1,10 @@
+valgrind (1:3.26.0-0codspeed4) UNRELEASED; urgency=medium
+
+  * feat: estimate cycles
+  * ci: remove samply walltime profiler and pinned runner version
+
+ -- Adrien Cacciaguerra <adrien@codspeed.io>  Mon, 22 Jun 2026 17:38:16 +0000
+
 valgrind (1:3.26.0-0codspeed3) UNRELEASED; urgency=medium
 
   * fix(callgrind): initialize stack on instrumentation start