[silverstripe] Add method (#532)

Parse https://raw.githubusercontent.com/silverstripe/roadmap/refs/heads/main/data.json to get release information.

Relates to https://github.com/endoflife-date/endoflife.date/pull/8932.

releases/silverstripe.json

@@ -2,78 +2,39 @@
   "releases": {
     "6.1": {
       "name": "6.1",
-      "releaseDate": "2025-10-31",
+      "releaseDate": "2025-10-13",
       "eoas": "2026-04-30",
       "eol": "2026-10-31"
     },
     "6.0": {
       "name": "6.0",
       "releaseDate": "2025-06-10",
-      "eoas": "2025-10-31",
-      "eol": "2026-04-30"
+      "eoas": "2025-10-13",
+      "eol": "2026-04-14"
     },
     "5.4": {
       "name": "5.4",
       "releaseDate": "2025-04-10",
-      "eoas": "2026-04-30"
+      "eoas": "2026-04-11",
+      "eol": "2027-04-30"
     },
     "5.3": {
       "name": "5.3",
       "releaseDate": "2024-11-04",
-      "eoas": "2025-04-30",
-      "eol": "2025-10-31"
+      "eoas": "2025-04-10",
+      "eol": "2025-10-11"
     },
     "5.2": {
       "name": "5.2",
       "releaseDate": "2024-04-15",
-      "eoas": "2024-11-30",
-      "eol": "2025-05-31"
-    },
-    "5.1": {
-      "name": "5.1",
-      "releaseDate": "2023-10-17"
-    },
-    "5.0": {
-      "name": "5.0",
-      "releaseDate": "2023-05-08"
+      "eoas": "2024-11-04",
+      "eol": "2025-05-05"
     },
     "4.13": {
       "name": "4.13",
       "releaseDate": "2023-04-26",
-      "eoas": "2024-04-30",
-      "eol": "2025-06-30"
-    },
-    "4.12": {
-      "name": "4.12",
-      "releaseDate": "2022-12-19"
-    },
-    "4.11": {
-      "name": "4.11",
-      "releaseDate": "2022-06-28"
-    },
-    "4.10": {
-      "name": "4.10",
-      "releaseDate": "2022-01-27"
-    },
-    "3.7": {
-      "name": "3.7",
-      "releaseDate": "2018-06-08"
-    },
-    "3.1": {
-      "name": "3.1",
-      "releaseDate": "2013-10-01"
-    },
-    "3.0": {
-      "name": "3.0",
-      "releaseDate": "2012-06-28"
-    },
-    "2.4": {
-      "name": "2.4",
-      "releaseDate": "2011-02-02"
-    },
-    "2.3": {
-      "name": "2.3",
-      "releaseDate": "2009-02-23"
+      "eoas": "2024-04-27",
+      "eol": "2025-06-10"
     }
   },
   "versions": {