build: fix log4j compilation error

Author: jknack

modules/jooby-log4j/pom.xml

@@ -19,6 +19,12 @@
       <version>${jooby.version}</version>
     </dependency>
 
+    <dependency>
+      <groupId>org.jspecify</groupId>
+      <artifactId>jspecify</artifactId>
+      <version>1.0.0</version>
+    </dependency>
+
     <dependency>
       <groupId>org.apache.logging.log4j</groupId>
       <artifactId>log4j-core</artifactId>

modules/jooby-log4j/src/main/java/module-info.java

@@ -9,6 +9,7 @@
   requires org.slf4j;
   requires org.apache.logging.log4j;
   requires org.apache.logging.log4j.core;
+  requires org.jspecify;
 
   provides LoggingService with
       Log4jService;