Update checkstyle version and fix gpg version (#79)

Signed-off-by: see-quick <[email protected]>

Author: see-quick

pom.xml

@@ -116,8 +116,8 @@
         <maven.compiler-plugin.version>3.11.0</maven.compiler-plugin.version>
         <maven.javadoc-plugin.version>3.5.0</maven.javadoc-plugin.version>
         <maven.source-plugin.version>3.2.1</maven.source-plugin.version>
-        <maven.checkstyle.version>3.3.0</maven.checkstyle.version>
-        <maven.gpg.version>1.7.1</maven.gpg.version>
+        <maven.checkstyle.version>3.5.0</maven.checkstyle.version>
+        <maven.gpg.version>1.6</maven.gpg.version>
         <sonatype.nexus.staging>1.7.0</sonatype.nexus.staging>
 
         <!-- FIX VULNERABILITY VERSIONS  -->