Fix ansible-test error in community.aws (#70507)

* Fix ansible-test error in community.aws

* Add changelog entry for fix

* Change check from None to string_types

* Update changelogs/fragments/70507-validate-null-author.yaml

clarify wording "or a list of strings"

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update test/lib/ansible_test/_data/sanity/validate-modules/validate_modules/schema.py

clarify wording - single string or not specified valid

Co-authored-by: Felix Fontein <felix@fontein.de>

* Do not fail but return None when given outside list

Co-authored-by: Felix Fontein <felix@fontein.de>

changelogs/fragments/70507-validate-null-author.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+  - Fixes ansible-test traceback when plugin author is not a string or a list of strings (https://github.com/ansible/ansible/pull/70507)

test/lib/ansible_test/_data/sanity/validate-modules/validate_modules/schema.py

@@ -412,15 +412,21 @@ def deprecation_schema(for_collection):
 
 
 def author(value):
+    if value is None:
+        return value  # let schema checks handle
 
     if not is_iterable(value):
         value = [value]
 
     for line in value:
+        if not isinstance(line, string_types):
+            continue  # let schema checks handle
         m = author_line.search(line)
         if not m:
             raise Invalid("Invalid author")
 
+    return value
+
 
 def doc_schema(module_name, for_collection=False, deprecated_module=False):