chore: remove old build constraints syntax

magefiles/config.go

@@ -1,5 +1,4 @@
 //go:build mage
-// +build mage
 
 package main
 

magefiles/download_forgejo.go

@@ -1,5 +1,4 @@
 //go:build mage
-// +build mage
 
 package main
 
@@ -51,7 +50,7 @@ func downloadForgejo(version string) error {
 	defer binary.Close()
 
 	client := http.Client{
-		CheckRedirect: func(r *http.Request, via []*http.Request) error {
+		CheckRedirect: func(r *http.Request, _ []*http.Request) error {
 			r.URL.Opaque = r.URL.Path
 			return nil
 		},

magefiles/mage.go

@@ -1,5 +1,4 @@
 //go:build mage
-// +build mage
 
 package main
 

magefiles/render.go

@@ -1,5 +1,4 @@
 //go:build mage
-// +build mage
 
 package main