fix: anchor checkver regex to match only JDK 26

Author: B67687

bucket/oraclejdk-26.json

@@ -17,7 +17,7 @@
     "checkver": {
         "url": "https://www.oracle.com/java/technologies/downloads/",
         "useragent": "curl/7",
-        "regex": "Java SE Development Kit ([\\d.]+) downloads"
+        "regex": "Java SE Development Kit 26.([\\d.]+) downloads"
     },
     "autoupdate": {
         "architecture": {
@@ -30,4 +30,4 @@
         },
         "extract_dir": "jdk-$version"
     }
-}
+}