update SHA256 checksum of plugin_installer plugin. Fixes #8904, #8884

org.gajim.Gajim.json

@@ -360,7 +360,7 @@
                 {
                     "type": "archive",
                     "url": "https://ftp.gajim.org/plugins_1/plugin_installer.zip",
-                    "sha256": "7d5dcd9a5e05d214ca85651784bda732aac3b5c363a6e23529e6e777f9d24d42",
+                    "sha256": "a4ee63a4b7fd213236f30f23ff0535d63bad2fd276363d4ac8d320da63d4d09c",
                     "dest": "gajim/data/plugins/plugin_installer"
                 }
             ]