Update Go and dependencies (#7)

Dockerfile

@@ -1,4 +1,4 @@
-FROM --platform=$BUILDPLATFORM golang:1.16.2-alpine AS builder
+FROM --platform=$BUILDPLATFORM golang:1.20.7-alpine AS builder
 
 ARG TARGETOS
 ARG TARGETARCH

go.mod

@@ -1,10 +1,17 @@
 module github.com/xperimental/goecho
 
-go 1.16
+go 1.20
+
+require github.com/prometheus/client_golang v1.16.0
 
 require (
-	github.com/golang/protobuf v1.5.1 // indirect
-	github.com/prometheus/client_golang v1.10.0
-	github.com/prometheus/common v0.19.0 // indirect
-	golang.org/x/sys v0.0.0-20210320140829-1e4c9ba3b0c4 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
+	github.com/prometheus/client_model v0.4.0 // indirect
+	github.com/prometheus/common v0.44.0 // indirect
+	github.com/prometheus/procfs v0.11.1 // indirect
+	golang.org/x/sys v0.11.0 // indirect
+	google.golang.org/protobuf v1.31.0 // indirect
 )