chore(toolchain): pin go1.26.4 to clear Go stdlib advisories

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

Author: AntoineToussaint

go.mod

@@ -2,6 +2,8 @@ module github.com/codefly-dev/service-python-fastapi
 
 go 1.25.0
 
+toolchain go1.26.4
+
 require (
 	github.com/codefly-dev/core v0.1.164
 	github.com/codefly-dev/service-python v0.0.1