Use psalm --shepherd

.travis.yml

@@ -24,7 +24,7 @@ jobs:
       install: composer install --prefer-dist --no-interaction --no-progress
       script:
         - '[ -z "$TRAVIS_TAG" ] || [ "$TRAVIS_TAG" == "$(php -r "require(\"vendor/autoload.php\"); echo Erusev\Parsedown\Parsedown::version;")" ]'
-        - composer test-static
+        - composer test-static -- --shepherd
         - composer test-formatting
         - composer test-dead-code
 

composer.json

@@ -18,7 +18,7 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^7.4||^6.5.13||^5.7.27||^4.8.36",
-        "vimeo/psalm": "^3.0.11",
+        "vimeo/psalm": "^3.2.7",
         "friendsofphp/php-cs-fixer": "^2.13",
         "infection/infection": "^0.12.0"
     },