upgrade to butane 0.20.0 and mux 1.8.1

Dockerfile

@@ -11,7 +11,7 @@ RUN cd src \
 FROM scratch
 
 LABEL org.opencontainers.image.title="fcct-service" \
-      org.opencontainers.image.version="0.19.0" \
+      org.opencontainers.image.version="0.20.0" \
       org.opencontainers.image.description="FCCT (butane) as a Service" \
       org.opencontainers.image.licenses="Apache-2.0" \
       org.opencontainers.image.source="https://github.com/zyclonite/fcct-service"

main.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"log"
 	"net/http"
 	"strconv"
@@ -25,7 +25,7 @@ func transpile(w http.ResponseWriter, r *http.Request) {
 	}
 
 	w.Header().Set("Content-Type", "application/json")
-	body, err := ioutil.ReadAll(r.Body)
+	body, err := io.ReadAll(r.Body)
 	if err != nil {
 		log.Printf("Error reading body: %v", err)
 		w.WriteHeader(http.StatusBadRequest)
@@ -60,7 +60,7 @@ func transpile(w http.ResponseWriter, r *http.Request) {
 
 func validate(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
-	body, err := ioutil.ReadAll(r.Body)
+	body, err := io.ReadAll(r.Body)
 	if err != nil {
 		log.Printf("Error reading body: %v", err)
 		w.WriteHeader(http.StatusBadRequest)

main_test.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"bytes"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -16,7 +16,7 @@ func TestValidConfig(t *testing.T) {
 	}
 	defer infile.Close()
 
-	dataIn, err := ioutil.ReadAll(infile)
+	dataIn, err := io.ReadAll(infile)
 	if err != nil {
 		t.Fatalf("failed to read %s: %v\n", infile.Name(), err)
 	}
@@ -45,7 +45,7 @@ func TestInvalidConfig(t *testing.T) {
 	}
 	defer infile.Close()
 
-	dataIn, err := ioutil.ReadAll(infile)
+	dataIn, err := io.ReadAll(infile)
 	if err != nil {
 		t.Fatalf("failed to read %s: %v\n", infile.Name(), err)
 	}