CI: Enable google-explicit-constructor

I was doing some refactoring before and was hit by one of the
constructors being magically called when i didn't want that.

Since we don't really on it (was just used in some of the explicit type
conversions) I think it makes sense to enable

And 2 small qt6 clang-tidy fixes because we don't have qt6 on
the clang-tidy CI yet

There's 2 potentially source incompatible changes in the qt frontend,
but i really really hope noone was using the constructors that way

1 files changed, 1 insertions, 1 deletions

diff --git a/qt6/tests/check_dateConversion.cpp b/qt6/tests/check_dateConversion.cpp
index 69be1724..d675a405 100644
--- a/qt6/tests/check_dateConversion.cpp
+++ b/qt6/tests/check_dateConversion.cpp
@@ -9,7 +9,7 @@ class TestDateConv : public QObject
 {
     Q_OBJECT
 public:
-    TestDateConv(QObject *parent = nullptr) : QObject(parent) { }
+    explicit TestDateConv(QObject *parent = nullptr) : QObject(parent) { }
 
 private slots:
     void initTestCase();