Make PHP-stan happy

.travis.yml

@@ -31,7 +31,9 @@ matrix:
         - name: PHPStan
           php: 7.2
           env: DEPENDENCIES="phpstan/phpstan"
-          script: ./vendor/bin/phpstan analyse src
+          script:
+            - ./vendor/bin/phpstan --version
+            - ./vendor/bin/phpstan analyse src
 
 before_install:
   - if [[ "$PREFER_COVERAGE" = true ]] && [[ "$TRAVIS_PULL_REQUEST" = false ]]; then TEST_COMMAND="composer test-coverage" COVERAGE=true; fi

src/Api/MailingList/Member.php

@@ -112,7 +112,7 @@ class Member extends HttpApi
      *
      * @param string $list    Address of the mailing list
      * @param array  $members Array of members, each item should be either a single string address or an array of member properties
-     * @param string $upsert  `true` to update existing members, `false` (default) to ignore duplicates
+     * @param bool $upsert  `true` to update existing members, `false` (default) to ignore duplicates
      *
      * @return UpdateResponse
      *