Remove invalid releases automatically (#466)

Automatically remove empty releases or releases which are released in the future, regardless of the product.

Also refactored a bit releasedata.py to use better names and clarify types.

releases/oracle-jdk.json

@@ -18,9 +18,6 @@
       "name": "6",
       "releaseDate": "2006-12-12"
     },
-    "5": {
-      "name": "5"
-    },
     "24": {
       "name": "24",
       "releaseDate": "2025-03-18"
@@ -86,21 +83,6 @@
     "10": {
       "name": "10",
       "releaseDate": "2018-03-20"
-    },
-    "1.4": {
-      "name": "1.4"
-    },
-    "1.3": {
-      "name": "1.3"
-    },
-    "1.2": {
-      "name": "1.2"
-    },
-    "1.1": {
-      "name": "1.1"
-    },
-    "1.0": {
-      "name": "1.0"
     }
   },
   "versions": {