[libcalamares] Expand YAML testing a little

- load/save of a stringlist seems to work

src/libcalamares/testdata/yaml-list.conf

@@ -0,0 +1,8 @@
+# YAML dump
+---
+"cow": "moo"
+"derp": 17
+"dwarfs":
+    - "sleepy"
+    - "sneezy"
+    - "doc"

src/libcalamares/utils/Tests.cpp

@@ -148,6 +148,7 @@ LibCalamaresTests::recursiveCompareMap( const QVariantMap& a, const QVariantMap&
 void
 LibCalamaresTests::testLoadSaveYamlExtended()
 {
+    Logger::setupLogLevel( Logger::LOGDEBUG );
     bool loaded_ok;
     for ( const auto& confname : findConf( QDir( "../src" ) ) )
     {