[gnome-games] flatpak: Pin down prboom commit

[Alexander Mikhaylenko <alexm src gnome org>]

commit a5625eee09da0f6a9afb9bc48527ac1a405baa79
Author: Neville <nevilleantony98 gmail com>
Date:   Fri Apr 3 16:35:34 2020 +0530

    flatpak: Pin down prboom commit
    
    commit: e3fd54321f385b7843fdb11cef1aeb000d450f00

 flatpak/libretro-cores/libretro-prboom.json | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/flatpak/libretro-cores/libretro-prboom.json b/flatpak/libretro-cores/libretro-prboom.json
index 0dde708a..ccadb232 100644
--- a/flatpak/libretro-cores/libretro-prboom.json
+++ b/flatpak/libretro-cores/libretro-prboom.json
@@ -17,7 +17,8 @@
             "sources": [
                 {
                     "type": "git",
-                    "url": "https://github.com/libretro/libretro-prboom";
+                    "url": "https://github.com/libretro/libretro-prboom";,
+                    "commit": "e3fd54321f385b7843fdb11cef1aeb000d450f00"
                 },
                 {
                     "type": "file",