parse floats safely in eks groovy job

jobs/build-snaps/build-release-eks-snaps.groovy

@@ -8,7 +8,7 @@ def _find_eks_base(version, override){
         return override
 
     // assumes the version looks like r'v\d.\d+.\d+'
-    def f_version = Float.parseFloat(version.substring(1, version.lastIndexOf('.')))
+    Float f_version = version.substring(1, version.lastIndexOf('.'))
     return f_version >= 1.99 ? "core22" : "core20";
 }
 def eks_base_override = params.eks_base_override