[bug-pqhgbnh8pqws] chore: upgrade Go toolchain to 1.27.0

Bump build base from golang:1.26.5-alpine to golang:1.27.0-alpine.
Update go.mod directive to 1.27.

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.26.5-alpine AS build
+FROM golang:1.27.0-alpine AS build
 
 WORKDIR /src
 COPY go.mod go.sum ./

go.mod

@@ -1,6 +1,6 @@
 module code.fritzlab.net/fritzlab/flock
 
-go 1.26.1
+go 1.27
 
 require (
 	github.com/containernetworking/cni v1.3.0