Add all missing deps for building flatpak

With this flatpak is now possible to build and working

pkgs/flatpak/lib/pango.json

@@ -0,0 +1,15 @@
+{
+    "name": "pango",
+    "buildsystem": "meson",
+    "config-opts": [
+        "-Dgtk_doc=false"
+    ],
+    "sources": [
+        {
+            "type": "git",
+            "url": "https://gitlab.gnome.org/GNOME/pango.git",
+            "tag": "1.47.0",
+            "commit": "43808377088ea3eecc1607b910dee1477508587b"
+        }
+    ]
+}