chore(deps): update go toolchain directive to v1.26.3

Author: renovate[bot]

go.mod

@@ -2,7 +2,7 @@ module github.com/rickli-cloud/headscale-console
 
 go 1.24.0
 
-toolchain go1.24.2
+toolchain go1.26.3
 
 require (
 	github.com/google/uuid v1.6.0