flatpak: use specific versions of svgwrite and pyxdg

flathub requires us to use specific versions, so let's do that here too so
we're consistent in testing.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

org.freedesktop.Tuhi.json

@@ -19,7 +19,9 @@
             "sources": [
                 {
                     "type": "git",
-                    "url": "git://anongit.freedesktop.org/xdg/pyxdg"
+                    "url": "https://gitlab.freedesktop.org/xdg/pyxdg",
+                    "tag": "rel-0.26",
+                    "commit": "7db14dcf4c4305c3859a2d9fcf9f5da2db328330"
                 }
             ],
             "build-commands": [
@@ -46,7 +48,9 @@
             "sources": [
                 {
                     "type": "git",
-                    "url": "https://github.com/mozman/svgwrite.git"
+                    "url": "https://github.com/mozman/svgwrite.git",
+                    "tag": "v1.3.1",
+                    "commit": "13633ad13d7a4b3253d1304d31db8fc2c8d1dd9e"
                 }
             ],
             "build-commands": [