fix #101

ImageMap.imdata

@@ -1,6 +1,6 @@
 #FileType HomepageImageMap
-23w51b.jpg https://lib.stapxs.cn/download/pic/image/23w51a.jpg
-23w51a.jpg https://lib.stapxs.cn/download/pic/image/23w51a.jpg
+23w51b.png https://lib.stapxs.cn/download/pic/image/23w51a.png
+23w51a.png https://lib.stapxs.cn/download/pic/image/23w51a.png
 1.20.4.jpg https://lib.stapxs.cn/download/pic/image/1.20.4.jpg
 1.20.3.jpg https://lib.stapxs.cn/download/pic/image/1.20.3.jpg
 1.20.3-rc1.jpg https://lib.stapxs.cn/download/pic/image/1.20.3-rc1.jpg

Library/Versions/2023/2023.json

@@ -642,7 +642,7 @@
       "type": "version",
       "versionID": "23w51a",
       "versionType": "Snapshot",
-      "headerImageUrl": "23w51a.jpg",
+      "headerImageUrl": "23w51a.png",
       "wikiUrl": "https://zh.minecraft.wiki/w/23w51a",
       "mcbbsUrl": "https://www.mcbbs.net/thread-1481805-1-1.html",
       "websiteUrl": "https://www.minecraft.net/zh-hans/article/minecraft-snapshot-23w51a",
@@ -654,7 +654,7 @@
       "type": "version",
       "versionID": "23w51b",
       "versionType": "Snapshot",
-      "headerImageUrl": "23w51b.jpg",
+      "headerImageUrl": "23w51b.png",
       "wikiUrl": "https://zh.minecraft.wiki/w/23w51b",
       "mcbbsUrl": "https://www.mcbbs.net/thread-1481805-1-1.html",
       "websiteUrl": "https://www.minecraft.net/zh-hans/article/minecraft-snapshot-23w51a",