[matomo-web] Revert "Drop "as builder""

[Bartłomiej Piotrowski <bpiotrowski src gnome org>]

commit 76bbeb373724cd4d25458087fb71a6e5efa48215
Author: Bartłomiej Piotrowski <bpiotrowski gnome org>
Date:   Mon Dec 28 23:37:59 2020 +0100

    Revert "Drop "as builder""
    
    This reverts commit b4e1eb11023907d53d00de856733d60b63f32135.

 matomo/Dockerfile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/matomo/Dockerfile b/matomo/Dockerfile
index 12cfc70..774984a 100644
--- a/matomo/Dockerfile
+++ b/matomo/Dockerfile
@@ -1,4 +1,4 @@
-FROM matomo:4-fpm
+FROM matomo:4-fpm as builder
 
 USER root