Update Docker base image

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1-alpine3.17 AS build-env
+FROM golang:1-alpine3.18 AS build-env
 WORKDIR /app
 
 # Copy go.mod and go.sum and download as distinct layers
@@ -10,7 +10,7 @@ COPY . ./
 RUN go build -o /app/dyndns-distributor
 
 # Build runtime image
-FROM alpine:3.17
+FROM alpine:3.18
 WORKDIR /app
 ENV GIN_MODE=release
 COPY --from=build-env /app/dyndns-distributor .

client.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"io/ioutil"
+	"io"
 	"net"
 	"net/http"
 	"net/url"
@@ -39,7 +39,7 @@ func (c *DynClient) Update(urlTemplate string, ip net.IP) (string, string, error
 	}
 
 	defer response.Body.Close()
-	body, err := ioutil.ReadAll(response.Body)
+	body, err := io.ReadAll(response.Body)
 	if err != nil {
 		return "", urlWithoutPassword, err
 	}
@@ -59,7 +59,7 @@ func (c *DynClient) GetExternalIp(ipRetrieveUrl string) (net.IP, error) {
 	}
 
 	defer response.Body.Close()
-	body, err := ioutil.ReadAll(response.Body)
+	body, err := io.ReadAll(response.Body)
 	if err != nil {
 		return nil, err
 	}

settings.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"os"
 )
 
@@ -26,7 +26,7 @@ func LoadSettings() (*Settings, error) {
 	if err != nil {
 		return settings, err
 	} else {
-		buffer, err := ioutil.ReadAll(file)
+		buffer, err := io.ReadAll(file)
 		if err != nil {
 			return settings, err
 		} else {