fix uninitialized variables

src/work-calendar.cpp

@@ -200,10 +200,10 @@ void per_frame(){
         
         //Legende
         ImGui::TableSetColumnIndex(1);
-        ImVec4 col;
+        ImVec4 col = {};
         ImGui::ColorButton("colortest", col);
         ImGui::SameLine(0, 0);
-        char buf[64];
+        char buf[64] = {};
         ImGui::InputText("", buf, IM_ARRAYSIZE(buf));
         //TODO