Increase minimum supported Chrome and Firefox versions (#1299)

We agreed to support back to the previous ESR Firefox
release[1] (currently 91) and Chrome releases for the past
year[2] (currently back to 92). We will bump these minimum version
numbers periodically in line with that policy.

1 - https://endoflife.date/firefox
2 - https://chromiumdash.appspot.com/releases?platform=Windows

browsers/chrome/manifest.json

@@ -3,6 +3,7 @@
     "description": "__MSG_appDesc__",
     "default_locale": "en",
     "version": "2022.8.25",
+    "minimum_chrome_version": "92.0",
     "icons": {
         "16": "img/icon_16.png",
         "48": "img/icon_48.png",

browsers/firefox/manifest.json

@@ -3,7 +3,7 @@
     "applications": {
         "gecko": {
             "id": "jid1-ZAdIEUB7XOzOJw@jetpack",
-            "strict_min_version": "65.0"
+            "strict_min_version": "91.0"
         }
     },
     "version": "2022.8.25",