Add missing jSpecify annotations

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/delete/DeleteDSL.java

@@ -120,7 +120,7 @@ public DeleteDSL<R> limit(long limit) {
             return limitWhenPresent(limit);
         }
 
-        public DeleteDSL<R> limitWhenPresent(Long limit) {
+        public DeleteDSL<R> limitWhenPresent(@Nullable Long limit) {
             return DeleteDSL.this.limitWhenPresent(limit);
         }
 

src/main/java/org/mybatis/dynamic/sql/update/UpdateDSL.java

@@ -202,7 +202,7 @@ public UpdateDSL<R> limit(long limit) {
             return limitWhenPresent(limit);
         }
 
-        public UpdateDSL<R> limitWhenPresent(Long limit) {
+        public UpdateDSL<R> limitWhenPresent(@Nullable Long limit) {
             return UpdateDSL.this.limitWhenPresent(limit);
         }