fix(blogo): missing RendererPlugin interface declaration

blogo/plugins.go

@@ -15,7 +15,10 @@
 
 package blogo
 
-import "io/fs"
+import (
+	"io"
+	"io/fs"
+)
 
 type Plugin interface {
 	Name() string
@@ -25,3 +28,8 @@ type SourcerPlugin interface {
 	Plugin
 	Source() (fs.FS, error)
 }
+
+type RendererPlugin interface {
+	Plugin
+	Render(src fs.File, out io.Writer) error
+}