[libcalamares] Fix tests

 - The test wants to read settings.conf, but by default it's run
   from way inside the build dir, where there is no such file.
   Go looking for one (but not too far).

src/libcalamares/Tests.cpp

@@ -62,9 +62,13 @@ void
 LibCalamaresTests::testLoadSaveYaml()
 {
     QFile f( "settings.conf" );
+    // Find the nearest settings.conf to read
+    for ( unsigned int up = 0; !f.exists() && ( up < 4 ); ++up )
+        f.setFileName( QString( "../" ) + f.fileName() );
+    cDebug() << QDir().absolutePath() << f.fileName() << f.exists();
     QVERIFY( f.exists() );
 
-    auto map = CalamaresUtils::loadYaml( "settings.conf" );
+    auto map = CalamaresUtils::loadYaml( f.fileName() );
     CalamaresUtils::saveYaml( "out.yaml", map );
 
     auto other_map = CalamaresUtils::loadYaml( "out.yaml" );