Check Spotless formatting by default build

Detected in the course of support-and-care/maven-support-and-care#77.

Author: ascheman

.github/workflows/maven.yml

@@ -23,7 +23,7 @@ on:
       maven_args:
         description: 'The arguments to pass to Maven when building the code'
         required: false
-        default: '--batch-mode --errors --show-version verify javadoc:javadoc'
+        default: '--batch-mode --errors --show-version verify javadoc:javadoc -Dspotless.action=check'
         type: string
 
       maven-version: