build: fix import of alternative check library

Author: jknack

tests/src/test/java/io/jooby/i2408/C2408.java

@@ -5,8 +5,8 @@
  */
 package io.jooby.i2408;
 
-import org.checkerframework.checker.nullness.qual.NonNull;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 
 import io.jooby.annotation.GET;
 import io.jooby.annotation.QueryParam;