Remove <S> in quarterly constructors

[DavisVaughan]

They are disallowed here in C++20, which is enforced by new versions of gcc (14.1.0 and up)

From CRAN

  Found the following significant warnings:
    quarterly.h:203:12: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:204:31: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:258:23: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:259:33: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:371:39: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:372:49: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:374:49: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:432:34: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:433:44: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:436:44: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:438:44: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:439:44: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    quarterly.h:440:44: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]