MAINT: Adopt go 1.16's embed feature (#1162)

* MAINT: Switch from esc to embed
* Simplify
* Update minimum go version in docs and pipelines
* go generate

build/generate/generate.go

@@ -2,32 +2,9 @@ package main
 
 import (
 	"log"
-	"os"
-
-	"github.com/mjibson/esc/embed"
 )
 
 func main() {
-	conf := &embed.Config{
-		ModTime:    "0",
-		OutputFile: "pkg/js/static.go",
-		Package:    "js",
-		Prefix:     "pkg/js",
-		Private:    true,
-		Files:      []string{`pkg/js/helpers.js`},
-	}
-
-	var err error
-	out := os.Stdout
-	if conf.OutputFile != "" {
-		if out, err = os.Create(conf.OutputFile); err != nil {
-			log.Fatal(err)
-		}
-		defer out.Close()
-	}
-
-	embed.Run(conf, out)
-
 	if err := generateFeatureMatrix(); err != nil {
 		log.Fatal(err)
 	}