fix(browsers): add release dates for Opera Android 75-78 (#22275)

* fix(browsers): add release dates for Opera 75-78

Sources (assuming release date = announcement date):
- https://forums.opera.com/topic/62482/opera-for-android-75?_=1701269694242&lang=en-GB
- https://forums.opera.com/topic/63567/opera-for-android-76?_=1701269694246&lang=en-GB
- https://forums.opera.com/topic/65830/opera-for-android-77?lang=en-GB
- https://forums.opera.com/topic/67255/opera-for-android-78?lang=en-GB

* Update browsers/opera_android.json

browsers/opera_android.json

@@ -424,21 +424,25 @@
           "engine_version": "110"
         },
         "75": {
+          "release_date": "2023-05-17",
           "status": "retired",
           "engine": "Blink",
           "engine_version": "112"
         },
         "76": {
+          "release_date": "2023-06-26",
           "status": "retired",
           "engine": "Blink",
           "engine_version": "114"
         },
         "77": {
+          "release_date": "2023-08-31",
           "status": "retired",
           "engine": "Blink",
           "engine_version": "115"
         },
         "78": {
+          "release_date": "2023-10-23",
           "status": "retired",
           "engine": "Blink",
           "engine_version": "117"