build: Add Blueprint compiler to Flatpak manifest

Signed-off-by: Felicitas Pojtinger <felicitas@pojtinger.com>

Author: pojntfx

com.pojtinger.felicitas.Multiplex.json

@@ -17,6 +17,18 @@
     "--talk-name=org.freedesktop.Flatpak"
   ],
   "modules": [
+    {
+      "name": "blueprint-compiler",
+      "buildsystem": "meson",
+      "cleanup": ["*"],
+      "sources": [
+        {
+          "type": "git",
+          "url": "https://gitlab.gnome.org/jwestman/blueprint-compiler",
+          "tag": "v0.12.0"
+        }
+      ]
+    },
     {
       "name": "multiplex",
       "buildsystem": "simple",