chore(deps): update go to v1.26.4

Author: renovate[bot]

go.mod

@@ -2,7 +2,7 @@ module github.com/envelope-zero/backend/v7
 
 go 1.25.0
 
-toolchain go1.26.3
+toolchain go1.26.4
 
 require (
 	github.com/gin-contrib/cors v1.7.7