chore: update checkstyle configuration

Change severity to warning

config/checkstyle/checkstyle.xml

@@ -189,23 +189,18 @@
             <property name="severity" value="warning"/>
         </module>
         <module name="ParenPad"/>
-        <module name="TypecastParenPad">
-            <property name="severity" value="error"/>
-        </module>
+        <module name="TypecastParenPad"/>
         <module name="WhitespaceAfter"/>
         <module name="WhitespaceAround">
             <property name="allowEmptyConstructors" value="true"/>
             <property name="allowEmptyMethods" value="true"/>
-            <property name="severity" value="error"/>
         </module>
 
         <!-- Modifier Checks                                    -->
         <!-- See http://checkstyle.sf.net/config_modifiers.html -->
         <module name="ModifierOrder">
-            <property name="severity" value="error"/>
         </module>
         <module name="RedundantModifier">
-            <property name="severity" value="error"/>
         </module>
 
         <!-- Checks for blocks. You know, those {}'s         -->