[chrome-gnome-shell] firefox: lower version requirements to 56

[Yuri Konotopov <ykonotopov src gnome org>]

commit 2b1a27ada46fd654e9c4e9b78325d1b53b94816d
Author: Yuri Konotopov <ykonotopov gnome org>
Date:   Wed Mar 21 09:34:58 2018 +0400

    firefox: lower version requirements to 56

 extension/manifest.firefox.json |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/extension/manifest.firefox.json b/extension/manifest.firefox.json
index fc12dac..32c4c14 100644
--- a/extension/manifest.firefox.json
+++ b/extension/manifest.firefox.json
@@ -2,7 +2,7 @@
   "applications": {
     "gecko": {
       "id": "chrome-gnome-shell gnome org",
-      "strict_min_version": "58.0"
+      "strict_min_version": "56.0"
     }
   },
   "options_ui": {