Update default builder to heroku:20

api/server/handlers/gitinstallation/get_buildpack.go

@@ -27,7 +27,7 @@ func initBuilderInfo() map[string]*buildpacks.BuilderInfo {
 	builders[buildpacks.HerokuBuilder] = &buildpacks.BuilderInfo{
 		Name: "Heroku",
 		Builders: []string{
-			"heroku/buildpacks:20",
+			buildpacks.DefaultBuilder,
 			"heroku/buildpacks:18",
 		},
 	}

cli/cmd/pack/pack.go

@@ -9,6 +9,7 @@ import (
 	"github.com/buildpacks/pack"
 	"github.com/porter-dev/porter/api/types"
 	"github.com/porter-dev/porter/cli/cmd/docker"
+	"github.com/porter-dev/porter/internal/integrations/buildpacks"
 )
 
 type Agent struct{}
@@ -33,7 +34,7 @@ func (a *Agent) Build(opts *docker.BuildOpts, buildConfig *types.BuildConfig) er
 	buildOpts := pack.BuildOptions{
 		RelativeBaseDir: filepath.Dir(absPath),
 		Image:           fmt.Sprintf("%s:%s", opts.ImageRepo, opts.Tag),
-		Builder:         "paketobuildpacks/builder:full",
+		Builder:         buildpacks.DefaultBuilder,
 		AppPath:         opts.BuildContext,
 		TrustBuilder:    true,
 		Env:             opts.Env,

internal/integrations/buildpacks/shared.go

@@ -32,6 +32,8 @@ const (
 	// Builders
 	PaketoBuilder = "paketo"
 	HerokuBuilder = "heroku"
+
+	DefaultBuilder = "heroku/buildpacks:20"
 )
 
 type BuildpackInfo struct {