Dockerfile: update base image to golang:1.21.4-alpine

Signed-off-by: Derek Su <derek.su@suse.com>

Dockerfile.dapper

-FROM golang:1.17-alpine
+FROM golang:1.21.4-alpine
 
 ARG DAPPER_HOST_ARCH
 ENV ARCH $DAPPER_HOST_ARCH

examples/distroless/Dockerfile.helper

-FROM golang:1.17-alpine AS builder
+FROM golang:1.21.4-alpine AS builder
 
 COPY main.go /main.go
 COPY go.mod /go.mod 

examples/distroless/Dockerfile.provisioner

-FROM golang:1.17-alpine AS builder
+FROM golang:1.21.4-alpine AS builder
 
 ARG GIT_REPO
 ARG GIT_BRANCH

go.mod

 module github.com/rancher/local-path-provisioner
 
-go 1.17
+go 1.21
 
 require (
 	github.com/Sirupsen/logrus v0.11.0